09 C2S, 116k miles.

using Motul 8100 xcess gen2, the car was using an alarming amount of oil. Roughly 1.1L/1000mi give or take. Blackstone analysis came back with no issues.

At shop’s recommendation given oil consumption, they switched to Motul 8100 Power. Both oils are 5W-40. After about 350mi, the car remains at the full line when checking the oil. I’m thrilled, but surprised. How can an oil change, holding viscosity and even brand constant, make such a difference?

 

The Motul Power is simply a formulation that has some ester in it. Not much, but some, and it has less detergents which means it may be a little better than the Xcess in certain applications depending on what your use case is. The oil usage, however, may not be as dramatic difference as you think..at least so far. You are at 350 miles and let’s say you drive another 50 miles and then the oil gauge goes down one bar. Well, you have 3 segments in your digital oil gauge so that means that all 3 segments would equal 1200 miles for the full quart of oil. That is not that different than your Xcess which you say gave you about a thousand miles per quart.

So, continue driving and see if it goes down a segment after 5 or 6 hundred miles. Then, that would be a more significant change. Perhaps your tech also overfilled the engine a little with that oil, so that could also explain why the level hasn’t moved down yet. I’d wait a little before you make that claim of it being a huge difference.

 

Post the UOA report

 

O

OK

 

Not bad. Iron is a hair high - just keep an eye on that for future samples. LM usually has high iron and copper and Motul higher iron, but your aluminum and copper look fine. Higher zinc & phosphorous content might help with the iron wear.