[Deakins]

I'm gonna go out on a limb here and say that they lost the 1 mpg on both transmissions due to the change in factory engine oil fill. If they are filling with 0W40 now they will have to test with it. If you look at the kinematic viscosity of a 0W40 compared to the old 5W30 at operating temp it's clear to see that the engine is working harder to pump the oil. The aero could share some blame as well but the oil change will hurt it right off the bat. There's no free lunch in this game.

[6sigma]

Originally Posted by Deakins

I'm gonna go out on a limb here and say that they lost the 1 mpg on both transmissions due to the change in factory engine oil fill. If they are filling with 0W40 now they will have to test with it. If you look at the kinematic viscosity of a 0W40 compared to the old 5W30 at operating temp it's clear to see that the engine is working harder to pump the oil. The aero could share some blame as well but the oil change will hurt it right off the bat. There's no free lunch in this game.

That's interesting, I didn't know they switched factory oil. With all the pressure on MPG today it seems like an odd choice to switch oils that loses MPG. In fact, much more common to see thinner oils used to help eek out that extra MPG (0W-20). A change to 0W40 seems like it would be done for some other reason because it might cause a MPG penalty.