Oil question

I went to an auction yesterday and they had some oil on the sale bill. A mix of weights and brands, my question is on some of the oils in the pile.
As I go thru the stash I may have more questions.
It's all old, in the types of cans that you poke one of those spouts in that today's kids haven't seen...
First one... Not all, but some of it is 20w20. Weird. What would use such an oil?
What would is 60-HD oil used for? Is HD heavy duty or Harley Davidson? My first thought was aviation
But among other things this particular stuff says on the can "Also meets specs for 1967 and older vehicles". I didn't think they were running thY heavy of oil in cars ever.