I have a 1971 Dodge Polara w/318, right now I'm using castrol 10W-30 and changing oil every 3K.
I'm getting ready to run a 1951 Chrysler Imperial w/fireball 331ci V8. What oil should I run in this car.
Mark
An older engine design like this would most likely do very well with a 10w40, or even one of the 10w30 high mileage oils, which are almost 10w40s in most cases, but seem to keep their viscosity better.