i run delo, what most the commercial fishing fleet uses in medium-heavy duty diesel engines up here in alaska. My skipper in my greenhorn year swore by it and his father was a SeaBee in the navy way back in WWII era and also learned heavy equipment mechanics and that is what he uses in his trucks, tractors, equipment. I've tried both rotella and delo and notice absolutely no difference in sound, consumption, or mileage, if delo is out, then i use shell, but i prefer delo, especially seeing a CAT3208 log 22,000 hours of punishment without a rebuild on a fishing vessel.