John, Have you tried rerefined oil? Some don't like to use it because they think it is used oil but actually refined oil is better. There are no detergents,additives and such. I think you are a military man right? My father was in the air force for many years and all they used in those fighter jets is rerefined oil. The oil was cleaner, could stand higher temps, and could withstand those high RPM's those jet engines produced without foaming. Check it out it is just a thounght. Ohh yea the oil is also cheaper

Stephen