sjagernauth

I use Royal Purple 20W50 and did oil analysis with last change, no issues. Several buddies also use it.

911RufRT

Motul 300V 15w-50

serval

I have always been confused by oil choices, and yes I have read most of the threads on this issue. I guess what mystifies me is that most people seem to stray from the factory recommendation which these days seems to be Mobil 1 0W40. Esthers, shmesthers, how wrong can it be to follow Porsche's advice even if one factors in all potential marketing non-arm length relationship between Porsche and Exxon?

Stealth 993

M1 isn't a true synthetic anymore. They had the definition changed to suite them. M1 is a "cracked " oil. While better then a lot out there, it is far from the "best" on the market. I want a true synthetic oil made from PAO, or Easters.

For me, it's going to be Amsoil, Redline, Motul, or Lubro-Moly.

Paddy

I used to use M1 20W-50 (red cap), but since it's NLA I've been using Swepco 20W-50.

matt777

Their recommendation doesn't come with a warranty and I can hardly believe they spend much time analyzing the needs of the air cooled cars which have been out of production for 14 years now The Mobil 0W40 is marginal when it comes to Zn and P content IMHO (which is based on LN Engineerings's Charles Navarro's recommendations). We'll never really know for sure what the consequences will be (if any) from running this oil or any other for that matter. Some claim to like one oil better than another but its never based on anything quantitative. How could it be?

Steve Weiner-Rennsport Systems

Hi Matt,

I think its fair to say that when a car shows up here with deeply pitted cams thats used one product for its whole life, one can draw some conclusions about that, compared to others without the same issue.

We've seen a lot more engines now (since 2005) with damaged cams (and rockers) than we ever did before (1975-2004) so we take careful note of what oil was used and how often it was changed.

Most folks really do not know whether their oil is any good at its job unless they disassemble the engine and measure everything. Thats why you talk to the people who have been doing this for a living for a long time,...

matt777

Yes, that was my point. There are some Porsche engine guys who have analyzed oils and run wear tests too. Porsche experts who have spent decades in the industry seem to be the best source of info IMHO. Funny how that works!

NC TRACKRAT

Call me "old school" or "geezer" but I want the stuff in my oil that the government has legislated out of it, namely higher levels of ZDDP. When it comes to choices, it's purely a matter of economics. I'd much rather pay to have my catalytic converter replaced than have my engine re-built!

scott watkins

Believe RP is standard issue with Mike Callas @ Rennsport, unless requested otherwise.

serval

I just read back though some of the threads and came accross a post from Doug Hillary that I think nails it perfectly... I'm taking the liberty to re-post here - hope he does not mind.
Again, credit for what is below belongs to Doug Hillary, not me. I am no expert on oil formulations.


Hello,
I hope that this post does not come across as being opinionated and/or dictatorial. My intent as always when the issue of lubricants arises is to try and dispel some mysteries and to alert non technical persons to the prospect of misinformation be it deliberate or not

Oil Formulations
It is extremely unwise to concentrate on certain aspects of an engine lubricant's formulation. It is true that too little or too much of some "elements" in an oil's formulation is counterproductive both from a wear and durability viewpoint

Steve - There are some anomalies in the "Navarro"paper and this is to be expected in such things. One glaring anomaly is in categorising of Delvac 1 5w-40 as a mineral oil. It is actually one of the best oil formulations ever made - it is a Group 4/5 synthetic with a significant Ester content. Another is classing Castrol's Syntec 5w-50 as a synthetic - it can be called that in NA but it is actually a semi-synthetic. There are a number of other anomalies in the paper

Perhaps instead of concentrating on some "old" oil formulation items a study that embraced engine oil operating temperatures as a possible cause of "excessive" wear may well have been productive. Many people endeavour to run their engine/oil too cold! Oil performs best above 90C and up to 120C depending on its structure (Mineral/Synthetic).
Running the engine's oil in a core temperature band of from around 92C -110C is most desirable. Too cold will inhibit the action of some Anti Wear (AW) chemicals and will eventually be destructive to the engine/oil's condition

Using Used Oil Analysis (UOA)
UOAs are a great tool for determining an oil's condition. In the hands of a well practiced person a UOA may well pin point abnormal component wear or other issues such as intake system leaks or some cooling system issues

UOAs are NOT a suitable device to compare one Brand of oil against another in regard to engine wear rates. Wear metals are recorded in Parts Per Million (PPM) and variability in readings are`well known. They are however an excellent maintenance "tool" when used within engine families but will NOT predict a sudden failure. They may well alert a smart person to a potential for failure

They can tell how an oil performs within an engine (loss/gain in viscosity etc) and in number of other critical matters such as the lubricant's ability to control acidity. They are`a great tool in determining when an oil change is required

Comparing wear metal rates in a 911 engine will mostly be an individual engine thing. This is called "trend analysis". Once additional oil coolers and other standard specification items are changed the metallurgical mix makes direct engine comparisons unreliable

Engine wear rates are precisely measured today in "real time" by Radioactive Tracer Technology and etc. and measurements made in nanometres (one millionth of a millimetre) per hour etc. This is done in clinical conditions with known metallurgy within the engine. Some of these radionucleide tests run for 1000 hours or so and many are engine component specific (cams, rings etc). On road (user) testing still plays a very valuable role and extends for many millions of kms and sometimes for years


Oil performance/quality Standards
The American Petroleum Institute (API) performance/quality standards were driven by the Oil Industry until the last several years. Engine makers (except Diesel engine makers) had very little say in the standards. This has produced some "issues" over the years
The API's latest SM oil formulation has proven to be mostly better than SL in service

The ACEA performance/quality standards are determined by the engine makers
Our engines should only use an oil with ACEA's A3/B3-96> rating - the API's rating is largely irrelevant

Steve - In Australia many of our lubricants are imported from NA or Europe. Some come from Singapore. All must meet either the API or ACEA standards - or both and we get the latest formulations very quickly. We have a very robust Motor Industry in Australia
Our choice of lubricants is a s good as or better than in NA

Motul 300V Competition 15w-50
Care should be take when using this oil in day to day operation. It is not intended for this type of application - Motul make much better oils for street use such as 6100 Synergie 5w-40
Motul are` good products but are no better or worse than any other same specification oils

Delvac 1 5w-40 (also known in NA as Mobil 1 Turbo Diesel 5w-40)
This is one of the most robust engine lubricants ever made. Some of its greatest attributes are retention of viscosity over long periods and in very high temperatures along with very low valve gear wear rates. It is not on Porsche's Approved List as it is really a mixed fleet diesel/petrol lubricant. It would easily pass the Porsche Test protocols

Supplementary Additives
The use of supplementary additives in engine oils was discussed in an earlier thread. IMHO it is unwise to add any supplementary additives to a modern engine lubricant - the risk of additive clash and other side affects is very real. That is the also the opinion of almost every engine manufacturer and Lubricant producer

Viscosity
Porsche's Approved & Listed oils are quite viscous at the SAE40 standard - these are 0w-40 and 5w-40. Only one SAE50 oil is Approved - Mobil 1 5w-50

Mind Over Motorsports - your success with Mobil 1 0w-40 is echoed by millions around the World. This is a fabulous product that is readily available - if expensive. Like many synthetics though, some people may lose a little oil pressure at idle over more viscous (or Mineral) lubricants. They gain many more advantages by the more linear flow rates which aids engine component cooling and component actuation speeds and etc

So, back to the title of this thread - "Best oil for a 993???". Chose one from the Porsche Approval List. These oils all meet the volatility, anti foaming, viscosity retention requirement and High Temperature High Shear viscosity protocols etc..over the ACEA A3/B3 test requirements. Mobil 1 0w-40 is what the Factory uses!!!

I hope that this is of some interest

Regards
Doug

chaoscreature

This is off topic but related,
What do your oil pressure gauges read, both at idle and at higher rpms? I started out using a Diesel Synthetic oil in my car, but the oil pressure seemed too high so I switched back to the European Blend 0W-40 Mobil1.

stahwille

Like religion and politicians, motor oil should be understood , (instead of over stated or misunderstood. PORSCHE FACTORY fill recommend MOBIL 1 SYN. The 15k recommended oil service interval is difficult to grasp for us old timers.... BTW SWEPCO offers free oil analysis. MJ.

NaroEscape

I ran Mobil 1 for 180k miles on my engine, then switched to Brad Penn at the recommendation of my mechanic.
the engine runs great, but has never been torn apart, so I can't comment on what's inside....there has been no reason to go in it, so I'm not.

IXLR8

Quite possible if a car has been serviced where a record is kept over its entire life. With you average 993 having had 3 or more owners and where the car has moved across the country to various shops, that would be kind of tough.