I have come late to this discussion but through personal experience, I disagree. My overhauled 1954 235 has 30,000 miles since overhaul and it leaked oil for most of that until last fall when I stopped using synthetic engine oil. Still, have a minor leak but not as much as before. After reading all the post, would a heavyweight oil effect
gas mileage, like 10-50?
Last edited by WE b OLD; 09/17/2017 11:56 AM.
