Originally Posted by CR94
Originally Posted by Bryanccfshr
It is more accurate if you track mileage for the entire OCI. ...
Yes, definitely so (for the formula that uses "mpg"). In fact, that's a thinly disguised version of one of my pet ideas, that for any particular oil+vehicle combination, change intervals would be better defined if based on total fuel consumed since the previous change, instead of simply on distance traveled. In that case, the other terms in the formula are essentially constants, but variations in idle time, weather, short trips, towing, etc. are reflected in the fuel used, hence in mpg.
The displacement/power term overly favors large, low-specific-power engines (e.g., pre-1950 tech), methinks.
I think it is about right. Higher power density producers such as GDI and turbo are penalized while more traditional engines are easier on oil. A 2.7 ecotech will wear oil faster than a 4.6 modular. I don't think that Direct injection is penalized enough. For the Micro soot and fuel loading. But like dusty roads, GDI is a penalty and restriction of its own that oil can't fix.