Quote:
Originally Posted by Peter Zimmermann
From a very trusted engineer in the trenches...
"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!
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!"
And then there's the viscosity thing recommended by Porsche.
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I agree that it is not just about the ZDDP, but given the relative parity of 2 oils in other areas, i'll take mine w/ a little extra ZDDP
I will have to go back and look at other approved oils but the last one I looked at dated 1/05 only has 0w-40 oils on it.