I worked in my father's garage during the 50's.
Most cars used "single weight" High detergent oil. 30w summer and 20-20w winter. Changed often.
Some olds timers would ask for non-detergent, and we sold it from bulk drum measure. My experiance with old engines is the hard running late in their life causes oil consumption and leaks. Avoid 10w40 modern oils,and try to stay with single weight HD products.
