I've run RP max cycle( not the 8.99 a qt. RP for cars) for 17000 straight miles in my 07 XB 12ss with not one problem, and I only change it once a year. @ crxtasy I can tell you as an automotive tech for 20yrs, that if an oil comes out the same color as it went in then it didn't do its complete job. One big job of the oil is to remove and suspend contaminates witch is what makes the oil turn dark. If it's still clean looking then it left all the contaminates (carbon,sulfer,dirt and other combustion byproducts) in the engine.