First off, this is NOT my car.
This car is a "Saturday afternoon" car. It has just over 3400 miles, and received its first oil/filter change with M1 10W-30 and a pint of Valvoline Maxlife Engine Protector (MLEP). The car is driven once a week, for 13 miles one way and 13 miles back. (26 miles total) Already, after Mobil 1 10W-30 and the MLEP was installed, fuel economy has dropped by at least 1 MPG.
I was thinking that the fuel economy drop might have been caused by the 10W-30, since it is thicker than the 5W-20. But now that I look at it again, the 10W rating compared to the 5W rating for the factory fill 5W-20. (An analysis of the factory fill will be posted in the next few days) The more I think of it, the more that it has to do with the MLEP. A VOA of the MLEP showed its viscosity at a good 40wt, thus might have caused the M1 to thicken into a mid-upper 30wt.
I was wondering if German Castrol 0W-30 would be a good match for this car, since during the 13 mile commute, the oil isn’t at its normal operating temperature for the majority of the trip. Thus, the 0W-30 would offer better fuel economy since its viscosity at 40C is lower than a 5W- or 10W- oil. That would be probably be the best way to offer a good balance of protection and fuel economy, since the German Castrol would probably be the same thickness as the M1 10W-30 right now, since it has the M1 has the MLEP right now.
The BITOG “take” on the subject?
Michael