I had a discussion with an auto parts store employee this weekend. It was about what oil one should/can use in their car. Keep in mind that this guy is about late 50's in age and drives a 1960's muscle car.

He feels that the use of 5-30, 5-20 weight oils is purely a tactic by the auto manufacturers to get the best gas mileage out of their engines. He feels that these low weights can actually damage the engine and we should all use weights like 20-50. I used to rebuild 60's and 70's cars myself and religiously used Castrol or Valvoline 20-50. I partially agree with the mileage ascertation, however, I contended that the engines are built with tighter tolerances now and need the lower weights. I use 5-30 synthetic in our 99 S70 low pressure turbo.

Just wanted to open this up to a discussion on the board.