Does every 4.4, 4.6 and 4.8

[TiAgX5]

Originally Posted by JCL

Then there are all the studies published by SAE and others that document lower engine wear with used motor oil than new. Makes a case for not changing the oil too frequently.

Some discussion here: used oil better than new? - Bob Is The Oil Guy

Haven't read thru it all yet, but seeing "in some cases" and "under certain circumstances" verbage in the SAE document makes me wonder.

Why would BMW do a low miles oil change on all high RPM ///M cars? To increase wear on these new, tight tolerance engines?

[JCL]

Originally Posted by TiAgX5

Why would BMW do a low miles oil change on all high RPM ///M cars? To increase wear on these new, tight tolerance engines?

Because of the surface finish on the cylinder bores, as I understand it. But they don't do it anymore, they are now using the same bore machining that they use on their non-M engines, so the 1200 mile oil change was discontinued.

I would suspect you actually want to accelerate the wearing in of the piston rings to match them up to the bores, so although it sounds counter-intuitive, yes, an early oil change would speed the bedding in process. Sometimes wear is a good thing.

[bcredliner]

Originally Posted by JCL

Because of the surface finish on the cylinder bores, as I understand it. But they don't do it anymore, they are now using the same bore machining that they use on their non-M engines, so the 1200 mile oil change was discontinued.

I would suspect you actually want to accelerate the wearing in of the piston rings to match them up to the bores, so although it sounds counter-intuitive, yes, an early oil change would speed the bedding in process. Sometimes wear is a good thing.

Or, perhaps they wanted the contaminated oil out of the engine before it caused damage. As an example, it is common to change the oil in highly modified engines after every race or even every pass.

[JCL]

Originally Posted by bcredliner

Or, perhaps they wanted the contaminated oil out of the engine before it caused damage. As an example, it is common to change the oil in highly modified engines after every race or even every pass.

In a race vehicle, changing the oil more frequently has to do with the very high heat the oil is subject to. IMO.

Changing the oil more frequently in those cases has little to do with making the engine last longer, as the engines tend to be rebuilt very frequently and long engine life isn't an objective.

[JCL]

I should qualify that I think changing engine oil regularly is a good thing. I just challenge the notion that doing it more frequently somehow results in reduced engine wear, compared to doing it at a higher mileage that is still well within the design guidelines for the engine and the oil.