Well I was always told to not use synthetic motor oil. But if you do all the research there is no diff in the oil except synthetic last longer. Most older folks will say no synthertic but thats cause they dont know the facts of it. Always add a zinc additive to gas motor oil. Rotella has a high zinc and will do good without a additive, cause diesels still use solid lifters. Rebuild a tune of high compression engines and have never seen anywere a note from an engineree saying to change oil after 1000 miles. Change oil at regular miles. Good luck
O ya. My 59 has the factory motor and is still runnning strong.
