Back in the 50 when I was an apprentice aircraft mechanic, the oil was SAE 60, 80, and 100 weight. Back then there was no HD oil, just straight mineral oil, so your car would use, on an average #30 weight oil. if you used the 60 oil in your car, it would never turn over in the winter. another point was, the oil was so thick, the oil ring couldn't scrape it off the cyl walls fast enough. The chief mechanic would put the used aircraft oil in his British Vanguard. When he drove away, you couldn't see the car for smoke.
Needless to say, I didn't stay at that airport for long.