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Frequently Asked Questions about Motor Oils

Do some oils make more horsepower than others?

ZDDP forms AW films only when there is metal to metal contact, so why do I hear that it is so important when there shouldn’t be metal to metal contact in the first place?

What oil should I be using to break in a new engine?

Can I use a diesel oil like Rotella to break in my engine?

How should I break in my engine if I don’t have access to a dyno to properly break in my rebuilt engine?

Which motor oil do I (Charles Navarro) use?

What viscosity motor oil should I use in my Porsche?

How did you determine the recommended 0.12% Zn and P level (ZDP, a.k.a. ZDDP)?

What motor oils had the 0.12% levels of zinc and phosphorus recommended?

Is there any potential problems with boosting the Zn and P in my API SM or CJ-4 oil or such a thing as too much ZDDP?

Why use a motorcycle oil?

Can I use a diesel motor oil in a car?

If new oils, with reduced zinc etc., are lacking in lubrication quality, why is it that engines are not being destroyed at a high rate?

Is there moly in my motor oil? Is moly bad for my engine?

What oil should I do if I have an older, higher mileage engine? Can I use a synthetic?

Should I use a semi or partial -synthetic or full-synthetic motor oil?

I have been running a non-detergent oil in my engine? Should I switch to a detergent oil?

I have been running detergent monograde oils, like Castrol HD30, in my classic car. Can I use a multi-grade?

I have always used synthetic oils. Can I switch to a non-synthetic?

What viscosity motor oil should I use?

Motor oils are superior today than what was available even a decade ago. Why does it matter what oil I use in my aircooled engine since they are “better” than what was offered when my engine was new?

What is sludge?

How can I get rid of sludge in my engine?

I want to learn more about how motor oils are evaluated. How is valve train wear tested for and measured? What other key factors go into evaluating a motor oils performance that pertains to my Porsche?

Who can test my engine oil? (used oil analysis)

What should I be looking for in an oil filter?

What if my engine does not have filtration?

What gear oil is best for my Porsche transaxle (manual gearbox)?

Does it matter what fuel I use?

What fuel system cleaner, lead additive, or octane booster should I use?

Do some oils make more horsepower than others?

Aircooled Technology and LN Engineering together just recently completed in January 2008 comparative oil testing of various non-synthetic, semi-synthetic, and full-synthetic oils with some very interesting results, which can be reviewed in our white paper titled “Evaluation of motor oils and their effects on engine output and efficiency.”

ZDDP forms AW films only when there is metal to metal contact, so why do I hear that it is so important when there shouldn’t be metal to metal contact in the first place?

This isn’t 100% true. Yes, there has to be metal to metal contact (friction) to form anti-wear films. What most naysayers don’t explain is that there are different kinds of lubrication – boundary and hydrodynamic are just two. Boundary layer lubrication exists where there is always metal to metal contact, like with the top piston ring, cam lobe, tappets, and rockers which makes up most of the non-corrosive wear. Hydrodynamic lubrication exists in areas like bearings, where in the best case scenario, there should never be any metal to bearing contact. The thickness and speed of formation of AW wear films on metal to metal surfaces has to do greatly with ZDDP levels, which detergents are used, and amount of pressure and friction between the surfaces in contact.

What oil should I be using to break in a new engine?

Ideally you want an oil with low or no detergency, no friction modifiers, be non-synthetic, and high levels of Zn and P, to make it as easy as possible for AW wear films to form on engine parts during this critical process.

We recommend running a break-in specific oil for the first 100-200 miles, with a change of oil immediately after initial cam break-in, and again at the 100-200 mile mark. If using this oil while breaking in your engine on a dyno, make sure to observe your oil temperatures and try not to exceed 210F to maintain optimal film strength with the viscosity of oil being used.

Can I use a diesel oil like Rotella to break in my engine?

Many cam manufacturers have recommended Rotella T in the past for cam break in. Remember, this was the CI-4 Rotella T some manufacturers were recommending, not the new CJ-4 Rotella. Be advised that we do not recommend the continued use of the new CJ-4 Rotella T for cam break-in or any other CJ-4 oil for this purpose. Additionally in support of this position, magazines such as Fleet Equipment, in one such article “Focusing on Oil,” stated that CJ-4 oils should only be used in 2007 and later diesel engines and that earlier diesel or mixed fleet engines should remain on CI-4 oils.

How should I break in my engine if I don’t have access to a dyno to properly break in my rebuilt engine?

Although not directly related to oils, I get asked this question very often. If you have questions on how you should break in an engine and proper break in procedure, we recommend reading the following articles about the subject:

http://www.mototuneusa.com/break_in_secrets.htm

http://www.aircooled.net/gnrlsite/resource/articles/engnbrkn.htm

Which motor oil do I (Charles Navarro) use?

For cars under warranty, we use primarily Motul 8100 X-Cess 5w40, which is still a mid-SAPS oil with higher Zn and P levels than the low or no-SAPS oils favored by manufacturers for emissions system protection. Both used oil analysis and physical engine teardowns have proven this lubricant to be a superior choice to Mobil 1. Although we are still fans of Brad Penn, outside of warranty, we recommend Joe Gibbs Racing lubricants due to how closely they have worked with Flat 6 Innovations and us in developing their oils for use in Porsche models.

Very important in my consideration of any oils are that they have the proper balance of Zn and P as well as level of detergency. Oils with high detergency need equally high levels of anti-wear additives as well as those oils using Ca-based detergents also need more Zn and P that those oils that use Mg and/or Na detergents.

I do not recommend using ZDDP boosters of any kind.

What viscosity motor oil should I use in my Porsche?

Porsche nicely answered this one for us (from ’84 911 owners manual). You can use a 20w50 year round, even with cold starts to 20F, which covers the majority of Porsche owners. I might add, if your Porsche is also your daily driver and you see repeated sub freezing (32F) starts, it wouldn’t hurt to use a 15w40 instead. The other recommendation frequently given by engine builders is that a 15w40 can be run up to 90F ambient air temperature and at higher temperatures, a 20w50 should be used.

84porscheownersmanualoilrec

Although the chart shows fuel-efficient oils, modern fuel efficient oils should never be used in your aircooled or watercooled Porsche. For modern water-cooled Porsche models, use of an appropriate 0w40 or 5w40 is recommended year-round and for the track, we recommend Joe Gibbs XP9 only. Always refer to your owners manual for the appropriate viscosity for your engine.

How did you determine the recommended 0.12% Zn and P level (ZDP, a.k.a. ZDDP)?

There are many excellent SAE technical papers on the subject, but the one I found most interested was from 1977 titled “Cam and Lifter Wear as Affected by Engine Oil ZDP Concentration and Type.” There is some background that is needed to shed light on their results. First of all, there are different types of ZDPs. There is an Aryl ZDP which is the most stable form. There is also an Alkyl ZDP which although is not as stable, exhibits the best wear protection.

In various fleet tests, it was determined that the best performance was from oils containting all Alkyl ZDPs or predominantly Alkyl ZDP blends. They also looked at the performance of “ashless” oils (0.03-0.05% Sulfated Ash) vs oils with normal levels (0.11% or higher) and it would appear that oils with lower ash levels needed more ZDP to provide the same level of protection. I bring this up since the newest CJ-4 and SM oils require significantly lower ash levels, less than 0.10%. Across the Indianapolis, Phoenix, and Los Angeles taxi fleets observed, oils with 0.11-0.13% Alkyl ZDP resulted in the lowest combined and average cam wear measured. Levels of wear remained low with oils with Alkyl ZDPs as high as 0.19%. Excessive Zn and P levels cam result in additional wear.

The oils that had at least 0.07% Alkyl combined with 0.05% Aryl performed just as well as oils with higher Alkyl only ZDP levels, suggesting some sort of synergistic properties of the decomposition products of the Alkyl/Aryl blend. Combined ZDP levels of the Aryl and Alkyl blend were min. 0.12%.

Our assumption with choosing a minimum Zn and P levels of 0.12% is on the assumption that the best combo of ZDPs are being used for wear performance, not longer drain intervals, with a motor oil that uses low levels of Ca-based detergents supplemented with Na or Mg detergents. Oils for long-drain intervals almost entirely use Ca-based detergents! Oils with Ca-based detergents in high concentrations need significantly more Zn and P, at least 0.145%. Swepco use Ca-based detergents and run additional levels of Zn and P of 0.145% or roughly 1450 ppm, as would be expected from an SL rated diesel oil.

The more detergent an oil is, the more anti-wear additives are needed. That means the correct amount of Zn and P in any given oil is a moving target.

More recently, in the development of the IIIG sequence, developers went so far as to say that there was no need for the VD and VE sequences for testing of OHV (overhead valve) engines because these engines are not commercially available as new anymore and do not reflect the needs of more modern engines. In a SAE paper titled “How Much ZDP is Enough?” from 2004, the resulting trend of decreasing phosphorus is as a direct result of observations that modern engines, with lower spring pressures and lighter vavletrain, including multiple intake and exhaust valves, seems to require only .03% Ph to prevent wear. It was further documented that by increasing to 180 lbs of spring pressure with a .03% ZDP resulted in 267 mil of wear where with .05% ZDP concentration tests resulted in 26 mil of wear. That same .05% oil with just 205 lbs of pressure resulted in 153 mil of wear, requiring .095% ZDP to reduce wear, resulting in just 16 mil.

The ZDP requirements of a motor oil are directly proportional to valvetrain spring pressure. Most older SOHC and pushrod aircooled Porsche engines have significantly more pressure, as a stock street pushrod Porsche 356 or 912 engine exceeds these levels of spring pressure compared to the levels of pressure on modern engines, for which oils are tested for. Newer oils will continue this trend, leaving older engines with fewer and fewer choices for motor oils compliant with the requirements of these older valvetrain, hence our recommendations for using oils with higher levels of ZDDPs as substantiated by earlier testing sequences and the results on engines similar to our older aircooled Porsches.

What motor oils had the 0.12% levels of zinc and phosphorus recommended?

The current API standard is SN and calls for 0.06-0.08% Zn and P, same as with the previous SM standard.

Here are the running averages for all the oils tested thus far, listed by their API rating:

API P (ppm) Zn (ppm) B (ppm) Mo (ppm) Ca (ppm) Mg (ppm) Na (ppm) Total Detergents
SE-SJ 1301 1280 151 357 1936 293 214 2443
CI-4 1150 1374 83 80 2642 199 2840
SL 994 1182 133 273 2347 109 22 2479
CJ-4 819 1014 26 2075 7 2082
SM 770 939 127 122 2135 13 139 2287

I do not recommend the use of any SM or CJ-4 (or later specification) motor oils in any aircooled Porsche, or any vehicle that can benefit from the added anti-wear additives such as pre-ODBII vehicles. If your vehicle is designed to use these newer oils or if your vehicle requires a manufacturer approved oil and is still under warranty, always follow your manufacturer’s recommendations!

What oil should I use in my newer Porsche requiring a “Porsche approved” oil, like the M96 or later Porsche engine?

We do not recommend use of most of the Porsche “approved” oils in any aircooled engine, including the 84 and later engines up to and including the 993 that are recommended to run these approved oils.

In the search for a “Porsche approved” oil, a quick glance at various Porsche owners manuals for a Turbo and GT2 as late as 2004 showed a recommendation for an API SH or SJ motor oil, so my recommendation is to find an approved oil with at least an API SL rating – an API SH or SJ would be even better. Additionally, try to use a 5w40 rather than a 0w40, as the viscosity with the narrower spread will have a higher high temperature high shear viscosity and should protect critical engine parts better at the upper limits. You do not need a 0w over a 5w until cold start temperatures are under -25C. Do not run any 0w30, 5w30, or 10w30 oil in your Porsche, aircooled engines included!

Coupled with Google and armed with the “overview of engine oils approved by Porsche “Porsche approval list”, including some oils that no longer have Porsche approval but were approved at some point, here are some suggestions for oils. Although previously possible to locate API SJ or SL rated Porsche-approved oils, it’s no longer possible to find any as they all carry SM or SN ratings on their labels, but for now, the Porsche approval rating requires a level of Zn between 0.10 and 0.12% while carrying the ACEA approvals, so try to choose a 5w40 viscosity over a 0w40 where appropriate (non-winter use). Outside of the warranty period, non Porsche-approved oils will likely provide better performance with shorter drain intervals, like Joe Gibbs DT40 or for the track, XP9.

Of additional interest is a German Porsche AG Technical Bulletin “2000 Motoroelfreigaben”, showing 10w40 as an acceptable viscosity, the only exception to this being the 2001 and later engines with Variocam requiring a 0w40 or 5w40. Since this system is sensitive to oil viscosity, too thick of an oil will throw a CEL, however we have tested XP9 for the track and its 10w40 viscosity does not cause any problems with the Variocam system for the track.

Is there any potential problems with boosting the Zn and P in my API SM or CJ-4 oil or such a thing as too much ZDDP?

Beware of ZDDP boosters and concentrates being sold under various names. These products should truly only be used at time of break-in or not at all if a fully-formulated break-in oil is used. I haven’t tested every one of these products, but one thing is very obvious to me. Products previously sold to boost ZDDP, like STP or GM EOS, always had roughly an equal amount of detergents to offset the affect of ZDDP in reducing the TBN of motor oil. Most of these ZDDP concentrates omit detergents altogether or use over-based Ca detergents known to reduce the efficiency of the anti-wear properties of the oil! Just like you need more Zn and P in an oil that has more detergents, you also have to have additional detergency because of the breakdown of ZDDP in peroxides and its interaction with combustion byproducts to form sulfuric acid. Knowing the right balance is something best left to the oil manufacturers and their chemical engineers. More acid, will increase the oils TAN, and will lead to corrosive wear of bearings. For once, I will have to say that more is not better, especially in this case. EOS and STP are decades old, and proven products that work synergistically with your existing motor oil and were never designed to boost the Zn and P more than 100-200ppm – unlike some recommendations to run double the ZDDP, in excess of 2000 ppm, which can lead to increased wear! It is not only the level of Zn and P that is important, but also starting with an oil that meets the ACEA A3/B3 standard would assure a starting TBN of 10 or higher and with similarly higher HTHS viscosities will also give you greater protection too. If you do choose to use these products, you must do used oil analysis to determine drain intervals and monitor overall TBN retention and ensure that the TAN increase does not lead to increased bearing wear! Too much ZDDP can also foul spark plugs and oxygen sensors, not to mention plug EGR valves and the catalytic converter. Additionally, lack of testing of these ZDDP boosters compared to fully formulated oils intended for racing or for older engines or even against SM or SN-rated oils side by side do not instill confidence in their performance, or at least at the time this was written.

Why use a motorcycle oil?

Motorcycle oils have higher levels of phosphorus/zinc for enhanced wear protection and the same high-temperature detergent technology for superior wear protection and engine cleanliness, even at elevated oil temperatures. Specifically motorcycle oils for aircooled engines are designed for very high localized oil temperatures and high overall oil temperatures, and typically have high flash points coupled with higher HTHS viscosities and lower noack% losses. As a whole, it would appear that all most motorcycle oils we tested have excellent anti-wear additive levels and most are not SM or SN rated oils, but rather earlier SG, SH, or SJ rated. In a pinch, it should be fairly easy to find a motorcycle oil with any of these SG, SH, or SJ ratings at your local auto parts store when it may be more difficult to get Brad Penn or Swepco, without having it shipped to you. Please do remember that motorcycle oils typically have levels of Zn and P that will kill catalytic converters, so if you have one, either remove it first or use another oil, like Brad Penn or Swepco. Also, motorcycle oils are not as detergent as the aforementioned Brad Penn or Swepco, so you must change the oil much more often, even though the perception of being able to go longer because the oil costs more is a false one.

Can I use a diesel motor oil in a car?

The newest CJ-4 formulations are now limited in the amounts of Zn and P allowed, compared to the CI-4 formations most users are familiar with. If the oil says CJ-4 or LE or “Low Emissions”, even if it also lists CI-4 or CI-4+, more than likely it conforms to the new, lower levels, and should be avoided unless you have a 2007 and later diesel which requires these oils. The verdict is still out in my opinion on the performance of a CJ-4 oil in our application. If you choose to use a diesel or mixed fleet oil, stick to an a CI-4 rated oil. Nowhere should the oil say for emission system protection or for use in engines equipped with particulate emissions filters. Swepco 306 15w40 is one such example of an extraordinary diesel oil favored by many Porsche engine builders. Swepco 306 has a healthy dose of boron and moly also for additional ant-wear response. Additionally, Swepco is among the minority of lubricant manufacturers choosing to manufacture and market the newer CJ-4 rated oils along since previous CI-4 and earlier lubricants to address the requirements of older engines rather than forcing backwards compatibility in fleet service. Although difficult to find, earlier CF-4 or CH-4 rated diesel oils have similarly high levels of Zn and P but are less detergent.

Worth noting, CI-4 diesel motor oils tend to have more detergents, and it has been determined in the SAE paper “Oil Development for Nascar” that overly detergent motor oils can block or “clean” the anti-wear films off of engine parts, that is one reason that these oils usually have high levels of anti-wear additives. SAE Technical Paper Series 2007-01-3999, Modern Heavy Duty Engine Oils with Lower TBN Showing Excellent Performance, also show that low detergent packages increase the effectiveness of film formation, just as in racing oils tend to have less aggressive detergent packages, which is another reason many be to consider a racing oil versus a diesel oil for your engine.

If new oils, with reduced zinc etc., are lacking in lubrication quality, why is it that engines are not being destroyed at a high rate?

Wear falls into two categories – catastrophic and non-catastrophic. Ever since the creation of the API SL standard, there have been more catastrophic cam and lifter failures from poor boundary (metal-to-metal contact) lubrication as well as corrosive bearing wear in areas with hydrodynamic lubrication. One industry wide solution was the supplemental use of EOS or switching to a racing oil, CI-4 diesel oil, or the use of oils specifically designed for older engines, like Brad Penn. Some companies, ours included, looked towards coatings for bearings and friction surfaces to remediate the problem, or even cutting edge materials like sintered silicon nitride composite followers to remove the wear component all together.

The other failure mode of engines with these poor performing lubricants was in non-catastrophic, measured in increased wear, as in bearings, cams, lifters, rockers, etc. all showing wear indicative of very high mileage or severe use in very few hours. The problem here is that most of the problems fall under the non-catastrophic, and may take years to surface. On a newer engine, like the M96, this wear may not cause any problems until the vehicle is out of the warranty period. Only when a catastrophic failure occurs, does an owner or shop take proactive measures to prevent this from happening again. All it takes is one catastrophic failure on a very high dollar engine to get a shop to make such a change, and until then, most shops continue to play Russian roulette whether they know it or not. The best preventative measure that can be taken with any engine is to change the oil often and use the best oil available, best meaning not expensive or full-synthetic, but rather an oil that is designed with high levels of anti-wear additives and the right balance of detergents.

The reformulation of motor oils was the primary cause of many of our problems with cam and lifters back in the early 2000s, however we turned to ceramic composite lifters before knowing the true cause of the problems, resulting in many failed pushrod VW and Porsche engines:

flatcamandliftersflatcamandlifters2flatcamandlifters1

badliftercloseup_1

1. Typical Conventional VW Type 4 Lifter after 50,000 miles of high performance street performance.

badliftercloseup_2

Conventional (what we thought was one of the best available) after only one dyno session and 65 miles of drive time. This one cost us $2500 to repair all the damage.

badbearing2

Rod bearings from same engine as lifter shown above. When you have a lifter failure, many other failures are just around the corner as the debris contaminates your oil and “extrude hones” the engine from the inside out.

 

A threesome of destroyed lifters. Note the lifter on the leftmost picture and it's height- this much of it was consumed by the camshaft and ingested by the engine. Between these three lifters, from three different engines, cost over $8000 in repairs between the three of them.

Note the lifter on the leftmost picture and it’s height- this much of it was consumed by the camshaft and ingested by the engine.

badlifterset

A set of eight lifters that were caught on the dyno just before total failure. They only had break-in and five hours of dyno time on them! We were able to replace these lifters with a set of ceramics and save this engine from total failure!

Shown below are two examples of non-catastrophic wear, discovered in two M96 engines at time of disassembly, caused by long drain intervals and use of motor oils not necessarily formulated with the best wear performance in mind. Like mentioned earlier, the factory recommended drain intervals may be too long and recommended “approved” oils may be best for your engine:

986sproketwear

Cam sprocket wear, 2.5 Boxster M96 engine, using Mobil 1 0w40 at factory recommended drain intervals, ~35,000 mi.

986tensionerpadwear

Cam chain tensioner pad, 2.5 Boxster M96 engine, using Mobil 1 0w40 at factory recommended drain intervals, ~75,000 mi.

Is there moly in my motor oil? Is moly bad for my engine?

From our testing, most SM oils have some level of boron and moly to make up for the lower level of Zn and P and is now more commonly found in SM oils and CJ-4 oils. In the development of long-life motor oils with reduced Zn and P, organic soluble moly has been added to help neutralize oxides formed in the motor oil from byproducts of combustion in addition to its use as a friction modifier to improve fuel economy and reduce engine wear in GF-4 and energy conserving oils. Some brands of oils have more moly than others, with Redline and Royal Purple using significantly high levels of moly in their lubricants. Some oil manufacturers claim that the addition of moly can reduce friction up to 38%, reduce bearing wear up to 60% and reduce overall operating temperatures.

On the flip side, some advertise their product does not have moly intentionally, claiming moly is an abrasive and deposit forming, which are both true in as much as ZDDP, although forming good anti-wear films, it increases friction and the oil’s traction coefficient. CMW Oil is one of the most vocal proponents of the elimination of moly all together from motor oils and does not use any moly friction modifiers in its street, race, or fleet lubricants. CMW is not alone in their recommendation against the use of moly in oils, with Cummins Engine Oil Recommendations, Bulletin No. 3810340-02, stating that “there is firm evidence that certain friction modifiers, molybdenum dithiophosphate for example, can in certain formulations result in cam follower pin failure at relatively low mileage.” Also, molybdenum compounds in motor oils can degrade and cause bearing corrosion and is particularly aggressive towards copper. In almost all cases, any engine oil formula having “moly” will also contain a copper deactivator which will protect bearings from the moly compounds. The only problem, the copper deactivator decomposes at relatively low temperatures and looses it’s potency after a few thousand miles, which can be seen in used oil analyses of moly rich oils having higher than normal copper levels. Additionally, there is documentation in various SAE publications showing a vast number of different species of moly friction modifiers, some providing better wear than fuel savings and vice-versa, and unfortunately, there is no easy way to determine how a friction modified oil is formulated other than to assume that a GF-4 and now GF-5 also known as energy or resource conserving oil is most likely to bias fuel savings for lower wear protection in thinner oils, like the aforementioned 5w20 viscosity so many import and domestic engines now require to meet CAFE requirements. Furthermore, the addition of start-stop technologies almost certainly require the use of zero weight oils to ensure immediate oil flow to prevent accelerated start up wear.

What oil should I do if I have an older, higher mileage engine? Can I use a synthetic?

We do not recommend high-mileage oils or high-mileage/stop leak/stop smoke additives because of the questionable formulation of some of these lubricants. Although not always the case, some high-mileage oils share the same improved HTHS viscosities and higher levels of anti-wear additives, such as with Mobil 1 10w40 High Mileage formulation. Regarding the whole synthetic versus non-synthetic debate, Brad Penn and Swepco oils are ideal for older engines, as they do not contain any of the Group IV or Group V synthetics- both the Brad Penn and Swepco products are highly refined parrafinic based petroleum oils. The only exception to this is the Brad Penn 0w30, which has 30-40% Group IV PAO base stock mixed in for additional low temperature and high temperature performance, exceeding some popular 0w40 fully-synthetic oils. Brad Penn’s Motorcycle Oils are overwhelmingly synthetic, using hydro-cracking to get their exclusive Pennsylvania crude to classify as a Group III synthetic, which is then blended with other synthetic stocks, to compete directly with Mobil 1’s motorcycle 10w40 and 20w50 oils. Most synthetic oils are formulated with seal swelling and conditioning agents to minimize the worsening of existing or formation of new leaks. That said, I have had mixed results. In my 911, which had been serviced with Castrol GTX 20w50 its entire life, I switched to Mobil 1. What was once a leak free engine now had substantial leaks, requiring attention. Once the leaks were addressed, the engine returned to being leak free and suffered from no new leaks. Also, since I have been asked, there is no problem switching back to a non-synthetic oil after having used a fully-synthetic, and in all my testing, I have switched back and forth between synthetic and non-synthetic oils many times without any problems.

Should I use a semi or partial -synthetic or full-synthetic motor oil?

In the SAE paper titled “Oil Development for Nascar Racing,” published in 2000, it was determined that a 50 weight non-synthetic motor oil provided the same level of protection as a fully-synthetic 30 weight, as long as the additive package is correct, so once again, it goes to prove that dino oils can perform as well as their fully synthetic counterparts and that to some extent, it is the additives that matter most. That’s why we recommend Brad Penn Racing oils and Swepco 306, both of which aren’t fully synthetic. They get the job done and have been proven to perform better than most fully synthetic oils in overstressed Porsche engines. Also realize that if an oil says partial synthetic, it probably is like the Brad Penn, only 10% synthetic, so the remainder of the Group I or II base stock used to formulate the oil is just as important, if not more so, than the small percentage of synthetic product used.

I have been running a non-detergent oil in my engine? Should I switch to a detergent oil?

First, if your engine has been run with a non-detergent oil for the majority of its life, you should stick to the non-detergent oil you have been using. Switching to a detergent oil will dislodge sludge and put into suspension everything that the non-detergent oil had left behind. Wait until you rebuild the engine or at the very least, although not recommended, if you really want to switch to a detergent oil, drop the oil pan, clean it thoroughly, and add an oil filter to the engine, if one doesn’t already exist. From what I have been told, you will want to change the oil countless times until the oil, after running for an hour or two, stays clean. Again, it has been suggested this might be five or six times, or even as long as 1000 mi with changes ever 100 or so miles. Using an engine flush product as well is a good idea, but make sure to follow the instructions provided, and you will need a few oil changes to ensure the the flush product itself has been completely purged from the crankcase and engine.

Beware of using engine flush products on modern engines with tight clearances, as they have shown to loosen sludge and deposits which can then lodge in other places in the oil system, causing lifter, oil squirter, and even bearing failures. If you are trying to flush a modern engine, consider several consecutive oil changes with very short intervals to more gently clean the inside of your engine.

I have been running detergent monograde oils, like Castrol HD30, in my classic car. Can I use a multi-grade?

Yes, there is no reason why you cannot switch to a 15w40 or 20w50. Just remember to choose a viscosity appropriate for your climate and engine (see chart above). Most 10w40 and lighter oils do not have sufficient levels of Zn and P, unless a motorcycle or racing oil with API ratings of SG, SH, or SJ. If you are running a straight weight oil in a race car that doesn’t need cold start protection, most monograde racing oils (like Brad Penn Racing 50wt) have lower detergency coupled with higher Zn and P, and are the obvious solution because of their higher flash points and sheer stability for cars run on the track hard, hot, and for extended periods of time under these conditions. These true straight weight racing oils do not have the needed detergency for extended use and should be changed after every race session and are not best for the street. Also, many race engines that use monograde 40, 50 or heavier weight oils also use sump or tank heaters to ensure the oil is already to temperature before the engine is started up, eliminating concern for wear caused at start-up by the reduced cold-flow characteristics typical of a thicker mono-grade oil.

I have always used synthetic oils. Can I switch to a non-synthetic?

This is a question we get often. Yes, you can switch oils as often as you like and can go between synthetics and non-synthetics all you want. You won’t hurt anything. In fact, every one of the cars in our combined test fleet get different oils every oil change as part of our used oil data collection to help evaluate the performance of various lubricants.

What viscosity motor oil should I use?

You should always refer to your owner’s manual for the recommended grade and viscosity of oil to be used in any engine. A good rule of thumb is your should always have 10psi for every 1000 rpm minimum at all engine temperatures, so choose a viscosity accordingly.

We are aware of the group of people who believe thinner oils are better for their engines. This is only the case if the engine is of a design requiring thinner oils or can support use of these thinner oils. Where choosing the thinnest oil to maintain the required pressure might seem logical, you have to also consider that you have a thinner oil film and lower HTHS viscosity for that thinner viscosity oil, which provides less protection in areas where metal to metal contact occurs where pressure itself only insures bearing protection, which has not been a problem we’ve ever experienced using higher viscosity oils like 15w40 and 20w50 viscosities.

Motor oils are superior today than what was available even a decade ago. Why does it matter what oil I use in my aircooled engine since they are “better” than what was offered when my engine was new?

Yes, most do agree that motor oils and the additives used today are more advanced than what was available in the 50s, 60s, and 70s for sure. That said, modern motor oils are governed by requirements dictated by auto manufacturers and API standards (among other standard bodies).

Most modern engines have dual overhead cams with four or more valves per cylinder, allowing for lower valvetrain mass and significantly lighter spring pressures, than what are used in older SOHC or OHV pushrod engines. One reason we need oils with more Zn and P is as follows: a good comparison is a stock Porsche 912 had about 200 lbs spring pressure; a Ford Crown Victoria, like those used in the Taxi motor oil study years ago by Consumer Reports and even earlier by GM in the 70s had up to 180 lbs, usually more like 160 lbs. A modern Porsche Boxster engine has only about 135 lbs over the nose. The amount of Zn and P that has to be used to protect valvetrain components is directly proportional to spring pressure and valve train mass. A high performance street pushrod or single overhead cam engine can easily have 300 or more lbs. of spring pressure or more if a race engine.

Most modern engines are water cooled, not aircooled, allowing for better control of localized engine temperatures. There obviously are exceptions to this- turbos are one exception that comes to mind. The oil used to cool (and lubricate) the turbos sees tremendous oil temperatures. Newer turbos are also water cooled to address the coking issue of localized very high oil temperatures typically found in turbos. Diesel engines also run higher oil temperatures than their gasoline fueled bretheren. These engines need higher HTHS (high temperature high shear) viscosities. Usually ACEA A3/B3 compliant oils are tested for this and must meet a minimum specification of 3.5 cSt. Most modern oils are not tested to see if it meets the ACEA A3/B3 requirements, as they are much more demanding than those imposed by the API.

Other examples are small displacement/high horsepower/high rpm engines, like BMWs M3 and M5, just to name two. They vary by manufacturer, but many have specific requirements when it comes to motor oils. Many of the manufacturer specific oils encompass the need for a very high TBN or total base number for long drain intervals while maintaining very strict limits on wear rates, again usually higher than what is specified by the API standards.

Porsche used to recommend in excess of two year/20,000 mi drain intervals on their newest cars, as does most every European auto manufacturer, which is too long in the opinion of many veteran Porsche mechanics and engine builders. In fact, Porsche reduced the interval to one year/12,000 mi just recently with the 2008MY, retroactive back to 1984, which if you didn’t know, is less than what Porsche recommended on the later aircooled engines in the 90s, using API SF-SH rated oils.

BMW and Mercedes even have oils and vehicles in which they call for 30,000 mi drain intervals. The demands of formulating a long life motor oil can directly impact the anti-wear properties, as Zn and P must be substituted out for other anti-wear additives, to improve the TBN retention of the motor oil and its detergents for the longer intervals. This is fine with newer, lighter valvetrains, but not the case with older engines that need those higher levels of Zn and P to provide the minimum levels to ensure adequate protection. We don’t need long drain intervals on our older cars.

Another consideration is that modern oils are for the most part designed with increasing the longevity of emissions control devices, not making your engine last longer. One good example of this is the new CJ-4 specification for diesel oils, for 2007 and later diesel engines with particulate emission filters or other emissions controls. One thing to remember is that most of our older Porsches and even some of the newer ones were designed to run Zn and P levels as found in API SE-SJ oils, even up to 2004, not these newer SL, SM, or SN rated oils!

What is sludge?

Another rampant problem is sludge formation. Many manufacturers have turned to synthetic oils to fight the formation of sludge, requiring owners to use synthetics meeting manufacturers stringent specifications due to the contamination, high oil temperatures, extended drain intervals, small filter capacities, and reduced sump capacities. Visit http://en.wikipedia.org/wiki/Oil_sludge for a list of cars suffering sludge formation and you can see this is a big deal. Another excellent link on sludge formation is http://www.schleeter.com/oil-sludge.htm.

White foamy sludge formation in our older aircooled and newer water-cooled engines can easily be solved by getting the engine (and oil) sufficiently hot (>212F) and doing so for at least 20 or 30 minutes at a time. Try to avoid starting up the engine and just letting it idle, as this just increases the fuel contamination in the oil. You do more harm not getting the oil up to temperature and putting serious miles on it than not starting it at all. Changing your oil after the car as been sufficiently driven and the oil is nice and hot also helps to get the moisture out of the engine and should be done before the car is put into storage for the winter, for those who don’t use their cars during the winter months.

How can I get rid of sludge in my engine?

Regularly changing your oil, usually more often than the manufacturer recommends, can prevent sludge from forming, if a quality oil is used. Remember, we usually go by the rule of thumb that an oil should be changed out when you get to 50% of the starting TBN, verified by used oil analysis. This ensures engine cleanliness without having to resort to overly detergent oils that are typically used for long service intervals.

Beware of using engine flush products on modern engines with tight clearances, as they have shown to loosen sludge and deposits which can then lodge in other places in the oil system, causing lifter, oil squirter, and even bearing failures. If you are trying to flush a modern engine, consider several consecutive oil changes with very short intervals to more gently clean the inside of your engine.

I want to learn more about how motor oils are evaluated. How is valve train wear tested for and measured? What other key factors go into evaluating a motor oils performance that pertains to my Porsche?

It is worth noting that modern engines have ligher valvetrain running lower spring pressures than most aircooled Porsche engines, so just because an oil meets one of the above ACEA requirements on their testbed, it doesn’t necessarily imply an equal level of protection or performance in your engine.

There are no current test sequences that guarantee the performance of modern oils in our aircooled engines or for that matter in any vintage or performance engine, even as late as 2004. Our best recommendations come from used oil analysis in real world testing as well as feedback from engine builders around the world who are clients of LN Engineering.

The European ACEA A1, A2, A3, B2, B3, and B4 classifications plate a cap on P levels at 0.10-0.12%. Additionally, ACEA A2 and A3 sequences require higher high-temperature high-shear (HTHS) viscosities, stay in grade sheer stability, and tighter limits on evaporative loss, high temperature oxidation, and piston varnish. This makes oils meeting these ACEA standards that much better for your Porsche, especially since wear limits are much more stringent for valve train wear, 1/6th to 1/4th the wear allowed in the sequences for API’s SM standard. Porsche requires a minimum 3.5 cSt @ 150C HTHS viscosity, which is a good measure of the protection any given motor oil provides. For the JASO JPI-5S-36 test procedure, a high temperature high shear viscosity of 2.9 mPa s min is required with shear stability performance less than that required of the ACEA sequences, so it’s best to look for an ACEA A2 or A3 in addition to any other classifications for a motor oil. It’s worth mentioning that the JASO test also has friction tests for addressing wet clutch requirements with a JASO-MA and MB, each testing its friction characteristic with respect to performance with wet clutches and the effect of friction modifiers on these clutches, but since we’re not worried with this for Porsche engines, I won’t elaborate. There is a new ACEA A5 classification for extended drain intervals using low viscosity low friction motor oils also requiring a HTHS viscosity of 2.9 to 3.5 mPa s. The A5 classification may not be suitable for an engine calling for an A3 or earlier and may not offer the same performance, where the A3 calls for a min 3.5 mPa s HTHS vis. Most test sequences and limits remain the same between A1 and A5 ACEA classifications except where the A3 and A5 add a sequence for DI (direct injection) piston & cleanliness & ring sticking and A3 and A5 oils have lower evaporative loss limit and all grades must stay in grade at 100C for 30 cycles, where an A1 does not.

Who can test my engine oil? (used oil analysis)

Used oil analysis is a valuable part of determining proper drain intervals and keeping an eye on the overall health of your engine. Once you have a VOA for a baseline of the oil you are using, a good rule of thumb for determining your drain interval is to change the oil when the TBN has been reduced to 50% of the original amount, unless testing deems an oil change is required earlier. This is more conservative than other recommendations to change the oil when the TBN is as low as 1 or 2. This means you should do a VOA (virgin oil analysis) of the oil you are using and you should order your oil tests with the optional TBN analysis to make that determination. If also testing for the TAN (Total Acid Number), when the TBN equals the TAN, then that is also an indicator that your oil needs to be changed.

In most cases, changing the oil at about half the recommended drain interval is a safe recommendation of how often you oil should be changed. In some cases, a manufacturers severe drain interval is exactly this, half the normal drain interval. Cars with track duty or severe service should consider even more frequent oil changes.

LN Engineering offers pre-paid oil analysis kits through the online store and provides electronic delivery of test results.

What should I be looking for in an oil filter?

It is very common to see the factory oil filter be the most recommended, and in our case it’s usually a Mahle or Mann oil filter. For sure, it does meet the manufacturer’s specifications, but we can do better. My filter of choice are Napa Gold/Wix filters for the majority of customers. For non-full flow filtration applications (where a bypass valve is employed), Mobil 1, K&N, Amsoil, or other high end synthetic media filters provide the best filtration and have excellent construction.

Due to the oil starvation issues associated with track use on Porsche’s M96 and M97 engines, we recommend the use of our billet washable oil filter with a 60 micron element, about double that of the factory filter micron size. However much smaller than the large 250 micron most racing filters employ, a 60 micron element is a good balance of flow and filtration that is good for both the street and track.

What if my engine does not have filtration?

Without filtration, regardless of how much money you spend on your oil, you will end up having to change your oil often. Remember, that doesn’t mean you should use a cheap oil!

Most stock engines have a spin on or cartridge style oil filter. In the majority of those cases, it’s a bypass filter, where only a small portion of the oil actually goes through the filter. It’s the idea that the oil is constantly filtering, so eventually all the oil will get filtered.

With full flow filtration, 100% of the oil goes through the filter. This does however require very high quality filters with HIGH burst strengths and durable construction, especially of the internal filtration media, because what’s the point of full filtration if the media just bursts and lets the contaminants out and doesn’t filter the oil?

Companies like Amsoil offer bypass filters designed to filter the sub 20 and 10-micron contaminants even down to the low single digits. Kits like these are designed to further lengthen drain intervals by removing all contaminants normal filtration cannot get out and are commonly used in fleet service in industries like trucking.

What gear oil is best for my Porsche transaxle (manual gearbox)?

There are many excellent choices for gear lubes, both synthetic and non-synthetic that are appropriate for use in our transaxles. I have had excellent success with the tried and true Swepco 201 80W-90 gear oil everyone has been using for years, but many do seek the benefits of a synthetic hypoid or gear lube.

For transaxles that call for a GL-4 spec gear oil, I have had excellent results with Amsoil’s fully synthetic GL-4 gear lube, not to be mistaken with a GL-5, which is “backwards compatible.” Another excellent GL-4 is manufactured by Redline, MT-90, which is a true GL-4 75w90 gear oil.

For transaxles that are compatible with GL-5 spec gear lube, you have many choices. Swepco for starters, being the most popular choice for gear lube among most Porsche owners. Another favorite of mine is Delvac 1 75w90 (previously known as Mobilube SHC), not to be mistaken with the Mobil 1 gear lube found at your local flaps. This stuff is the factory GL-5 fill from Porsche and is an industry standard in semi / mixed fleets, where a limited slip differential is not employed.

For applications with limited slip, please refer to manufacturer for a lubricant recommendation.

Does it matter what fuel I use?

Yes. Only use “Top Tier” fuels. Cheaper fuels may not have the detergency or lubricity required of high performance engines. It is worth noting that auto manufacturers, such as BMW, helped to establish the requirements for these top tier fuels to meet the needs of their engines. Fuels with lower levels of sulphur also typically result in less engine wear as well. Also, if your car calls for high octane fuels, don’t skimp. Modern engines that can benefit from high octane fuels will loose fuel economy if lower octane fuels are used. Lastly, if the engine is built for high octane, running less than required can result in engine damage or failure.

What fuel system cleaner, lead additive, or octane booster should I use?

Fuel system cleaners are widely available from dozens of companies, all promising everything from helping you to pass emissions testing to increasing octane. Many do little more than put a drain on your wallet. In most cases, using a quality pump premium formulation is the best thing you can do for your engine, regardless of octane requirements. Most modern engines and fuel management systems can adjust for the increased octane and provide improved fuel economy and horsepower, so even though the octane requirement may be 87 or 91 octane, it can benefit from 93 or even 94 octane.

If you want to use a fuel system cleaner, we recommend Joe Gibbs Driven Carb Defender. Driven’s Carb Defender Fuel Additive is specifically formulated to protect against Ethanol corrosion and induction deposits. Special corrosion inhibitors work to prevent expensive repairs and diminished performance caused by Ethanol-blended pump gasoline and the moisture it attracts. This additive controls combustion chamber residue, plus it cleans and protects surfaces of the fuel system and intake tract.

Another tried and true product is one made by Redline that is good for both fuel injected and carbureted engines, called SI-1. They also make a lead substitute, called just that, Lead Substitute, that also cleans your fuel system and is safe for injectors and catalytic converters. Both are excellent products ok for continuous use or occasional cleanings.

Another product endorsed by many Porsche owners is Chevron’s Techron Fuel System cleaner. There are many versions of this cleaner, but it is the most expensive one (with the highest % of Technron) that does the trick. The only caveat is that many owners recommend this cleaner should be used just before you change your oil, as the fuel system cleaner can contaminate your motor oil.

Additionally, Swepco’s 503 gasoline and diesel fuel improver is an excellent fuel system cleaner, but can be expensive to ship because of hazardous material charges.

Lubro-Moly also offers several professional grade fuel system products used by OEMs (as well as other cleaners for cooling system and engine) that are excellent.

Regardless of which you choose, I recommending using these products at least every time you change your oil (preferably before you change it!).

If you need to boost your octane, again, if you have access to race gas, that’s your best bet for a guaranteed octane boost. That said, Torco makes two race gas concentrates. One is unleaded and safe for use with catalytic converters and for street use and the other is leaded (with real lead) for OFF-ROAD USE ONLY. But keep in mind that lead gets into the oil and will cause accelerated wear, so try to keep lead additives or leaded fuel limited to race engines that get oil changes frequently.


References and Acknowledgements
Internet BMW Riders- Is this the right oil for my bike? http://www.ibmwr.org/otech/oilreport.html
Lubricant Additive Interactions, Surface Reactions and the Link to Tribological Performance in Engines. J.H. Green, A. Morina, M. Priest, A. Neville. Institute of Tribology, School of Mechanical Engineering, The University of Leeds, Leeds.
Motorcycling- The Honda V4 Files and More. http://www.math.uwaterloo.ca/~rblander/oil_opinion.html
A.T.I.S. FAQ on Motor Oils. http://www.atis.net/oil_faq.html Interpretation of experiments on ZDDP anti-wear films through pressure-induced cross-linking. N.J. Mosey. Tribology Letters 0 (2005). Myths and Legends 1. Zinc, Diesel Oils and API. Pennrite. Technical Bulletin No 85 May 2005. Oil is killing our cars. Keith Ansell. http://www.ttalk.info/Zddp.htm

Any information you may receive related to this web site is provided merely as friendly suggestions, not as expert opinion, testimony or advice. Neither LN Enginering nor Charles Navarro endorses or sponsors any information, products or methodologies you may find herein.

The test results contained herein come with no guarantee, even for a product with the same name, date code, API code, or lot number – there can and will be variations depending on the sample and who is doing the testing. Only the individual companies can assure that, and only they can report their specs.

 

Charles

About Charles

Inventor and developer of IMS Retrofit and IMS Solution, Charles Navarro is an owner and CEO of LN Engineering – manufacturer of Nickies™ Performance Cylinders and Sleeves. he's also a co-owner of Bilt Racing Service.