[Terry, NJ]

About once a month this subject comes up. The answer is every thing! I know of no stories of someone ruining a Mod. A engine because of using the "wrong" oil! Since a Mod A's oil does not stay in the engine very long. It was originally changed a 500 mile, but with today's better better oils, most change at 1000 miles. Most use a multi weight oil, 15-40 Shell, Rotella is preferred. Some prefer to stick to single weight like sae 30. Today the old argument about "Detergent" oil Vs "Non detergent" oils has evolved into Synthetic Vs non synthetic! But for now, I use the Shell Rotella available at Tractor Supply in 2 1/2 gal containers. But what ever oil you use, add some STP to it. For cars parked for a while it protects the cam, cyl. walls and other parts from from moisture. If this forms a thin coat of Iron oxide, It will be scraped off and contaminate the engine. These surfaces must be protected! The STP will protect longer than just the oil alone.
Terry