guy who changed your oil's a tool, you should be using
thinner oil, if anything different, with older cars, to put less stress on the engines. but since every old car has a leaky seal or two, you'll end up having to put oil in it more often when you go to a thinner oil, but as long as you consistently check the oil levels, you'll be better off with a thinner oil.
i drive an 88 camry with 160k miles (still gets 33mpg, holla) so i know my way around beaters