I have been changing my own oil since 1988 (18 y/o w/a 1979 Chevy Van). Then I went to a '90 Cavalier Z24, then a '94 Gran Prix, then a '90 240SX, '01 Olds Alero and now a '00 Max.
All this time I have been of the mindset: 10W30 in the winter, 10W40 in the summer. Living in TN, I always liked...