I have an 06 Workhorse 8.1 I have been running 5 30 Valvoline I have 55.000 miles now and was wondering If I should change to 10 30 or go to Mobil 1 or just stay with what I have been doing ! I live ...
Big advantage of synthetics is their ability to stick to the metal surface, lowering wear on dry start up and also protect the engine in case of failure. I had broken oil pump on my Mercedes and it run for couple of minutes with no oil pressure. Later on I was replacing head gasket and the engine at 300,000 miles still had factory crosscuts on the cylinders. Synthetics also allow lower weight, what saves fuel.