i managed a jiffy lube for 2 years and we had the mobil one rep. in and he told us that if u started running synthetic before 30000 miles then u could expect the car to benefit from it. now if u start using it at 150000 then u are just wasting your time. the valvoline man sold me on the vr1 race oil in an sae 50 and i wont use anything else. people say god thats sooo heavy but its perfect for a hard daily driven honda. please believe it...................