Soooooo.................what's the best oil to use in our cars?

 

Amsoil 20W50 if you have no leaks, Valvoline VR1 Racing for street...

 

Here is more on the subject of

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I have reservations about the "selling" of the API's petrol engine lubricant quality standards and IMHO if you own a Porsche you should "tune in" to the ACEA's quality standards, and then the Factory's lubricant specifications become much more meaningful

There are many theories and much conjecture about the relevant merit of the level of ZDDP in engine lubricants today. But it should not be just about ZDDP - it should be about the lubricant's additive "package". There is no doubt that when used at near minimum levels and when combined with complimentary additives (esters and etc) the wear rates are at least the same or better!

What is ZDDP (Zinc Diakyl Dithio-Phosphate)? It is primarily a boundary lubricant and being "multi skilled" it is an excellent anti oxidant (AO), Anti Wear (AW) and Extreme Pressure (EP) ingredient and a mild Friction Modifier (FM) too. So the residual "film" from its EP/AW role is now being duplicated by more advanced and in most cases ashless chemicals. Remember that "the film" actually reacts with metal surfaces forming a sacrificial shearing layer and imitating the metal to metal shear that would otherwise occur

Combining huge doses of any supplementary additive into a well blended lubricant will cause additive clash and even quite small doses may cause the same effect
The ZDDP component alone can contribute up to around 20% of the Sulphated Ash (SA) level in blended lubricants. The oil's SA level has a direct relationship to the level of piston and ring deposits - and bore wear!

So the level of ZDDP in a lubricant should not be judged as stand alone - the oil's overall AW, EP and FM performance is in the sum of its parts! This is why many semi-synthetic engine lubricants are now performing better than their fully synthetic brothers - the base stock, modern processing and new additive packages have produced excellent products!

Now, back to why the Euro engine Maker's lubricant specifications is so critical.
Firstly they want to protect their huge development costs and image and to maintain competitiveness under warranty. They are after Brand loyalty after reliability!
(Very few people know for instance that the BMC Mini never really returned a black dollar during its many decades production cycle)
Secondly to set their quality criteria the engine Maker will take the ACEA's protocol as a baseline. They then conduct clinical laboratory tests on "known" engine types (they have thousands of UOAs, warranty data and etc) where wear rates are measured over say 1000hrs in nanometers (one millionth of a mm) per hour and perhaps using RadioActive Tracer Technology.
Thirdly, they conduct very comprehensive field trials too, sometimes over several years
Some field trials extend into purchaser's use and application in the "real world"
Lastly - as indicated the Thirdly above, the engine's Warranty history is carefully evaluated at unprecedented levels today. Thanks to the Japanese!!!!!

So with Porsche (and other Euro vehicle makers too), their Approved lubricants List is not a sales pitch but a very serious database of lubricants that can do the job!

As for "excessive" wear;
was an Approved oil being used?
was the engine in good condition?
has the engine been used as intended?
how was the "excessive" wear quantified?
is there a reliable history on the engine?
is there a common history of this event or is it a "one off"?
And etc. It is so easy to base "facts" on a little bit of fiction and some licence

IMHO when using an Approved Oil (and see previous Posts on HDEOs) these things are paramount to maintaining an engine in peak condition;
1 - regular servicing, including an OC with new OEM filter at the prescribed intervals
2 - getting the lubricant quickly up to >90C and keeping it below 120C
The oil's Brand matters very little in practice!

glenncof - I agree with your Post. I have consistently referred to the Porsche Approved oils List (TSB) and the ACEA A3/B3 specifications. Alternatively I have always used HDEOs where the engine Maker's specifications were unclear or seriously outdated
I use Delvac 1 5w-40 in my 928 because the viscosity is correct and it's formulation is slightly more robust than some other M1 products - and I have a very long history with it in many engine types
Of course it is NOT Approved by Porsche as it is an HDEO and has not been tested by them

bgiere - Yes, as with most motor engineering issues correct assembly is the key to longevity - just ask BMW about their M Series!
For race engine applications careful consideration must be made but generally the HTHS viscosity needs to be robust (perhaps 4 to 5cSt) and according to the technologies employed. The viscosity perhaps may need to be higher than stock to compensate for ?? level of fuel dilution

High camshaft lobe wiping loads (high lift/heavy springs and injector actuators) are not new of course and have been a feature of most high speed heavy diesel engines produced since the 1970s. Many such engines have supplementary engine brakes (Jake, C Brake etc) too and these place enormous loads on the camshaft at speeds less than about 1200rpm. And in the 1970s there was a lot of failed camshafts!

To meet the API's "C" standards 5w-40/15w-40 HDEOs must have a HTHS viscosity above 3.7cSt (Porsche's minimum is 3.5cSt) and the synthetic versions are usually up around 4cSt. As well they have excellent thermal stability, low volatility, great viscosity retention and corrosion protection when used in petrol engines. And excellent anti foaming controls too! These are all excellent attributes in a lubricant used in dry sump engines and I suspect they are just other reason why Porsche used them for so long - around 30 years - as a Factory fill

This is why in earlier Porsche engines (pre 1984) an HDEO (mineral 15w-40 or 5w-40 synthetic) is such a good choice as you already know and as discussed earlier

Caution - All HDEOs are not built the same and any HDEO used in a petrol engine must be dual rated (example CI-4/SL). Some diesel engine only lubricants have very high SA levels and this may lead to excessive engine wear in some engines as noted earlier
These lubricants will just show the "C" rating (such as CI-4) on their container

Loaded - many on here probably think that I am very opinionated too!!!

As an example, there are too many "I"s in here - sorry. Some of the terms and definitions used in here are mine and are designed to make the meaning more obvious - I hope it works!!!

Regards
__________________
Doug Hillary
Rennlist Member # 030204-2681/060810-4400
01 Boxster (986) 2.7 Tiptronic
06 Mercedes Benz CLK Kompressor
(now sadly sold - MY89 928S4 Auto)

 

No, really...what's the best? (<-- insert sarcasm here)

I guess my point is this: is there really a right/wrong answer here?

 

awesome. ...and I feel sure that you already know the answer to that question.