Well, once I actually started paying attention to my car and what it needed, how it worked, and keeping it in good shape in my early 20s it was Havoline full synthetic 5w30 for $2.99 a qt. Prior to that I didn't pay much mind to what I put in my car in terms of oil. Now I always ran Amoco ultimate 93 in my cars. My step father worked at the Amoco refinery nearby.
My first car.. Dodge Omni where HP stood for Hamster Power.
Second car was the Mercury Tracer that my sister had owned. Ran well, very well in fact.
Third car was Ford Probe which was red, very nicely equipped. The car had a lot of miles on it with 147k. But it ran great for the next 4 yrs I had it. When I gave it away it had 227k miles on it. If I would have taken better care of it then it would've done much better. But I have no idea what oil I put in any of those cars.