Ran straight 30 weight in my 63 Falcon for years, then a guy in Akron asked me one question
He asked what oil pressure I had at hot idle and I admitted I never checked, so I put a gauge on it and saw 12 psi, which is way too low. Switched to 10w40 and now it sits at 30 psi warm, so has anyone else been fooling themselves on oil weight like I was?