4. Conventional motor oil as standard.
The synth oil commercials were true. I worked in Auto research and development. Oil companies stopped testing synthetics as they wouldn't fail in a timely manner.... We'd only test conventional with additives to see if they'd go longer than a week. Only barely did they a couple of times. Oil pump is the first to go. Won some good bets during that time hehe.
Edit: As I was typing this, memories came back. I remember taking oil samples on some of them. Nothing would come out so you let the test keep going. At the end, you had to have a sample, so we'd take the oil pan off with a pry bar to find oil cake... not sludge... nothing remotely 'fluid' anymore, just dry, thick, baked on carbon. You'd chisel some off and more than likely, toss the pan.