These engines were built with tolerances where 30 weight oil was recommended in the summer and thinner in the winter. IMHO 5 weight oil is too thin. Keep in mind any modern oil provides better lubrication that 1950 oil. A lot of folks use 10W30 with great success. I use 15W40 year around in my 38 and 53. Personally I would never use non detergent oil in any engine at any time.

Last edited by Tiny; 06/16/2021 3:54 PM.
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