I used to be a mechanic so I don't like paying for service I can perform for myself. So I change my own oil. I use Castrol synthetic in my car, put the old oil back in the container I just emptied. My children think I should change theirs as well so the rest of the oil came from their cars. Also Castrol but not synthetic. I think there may be some ATF from my son's car. When my son mixed a little antifreeze with some it did not go into my used oil bottles.

Actually I would rather pay someone else to work on my cars but since I am currently unemployed I can't.