I've been using Mobil 1 15-50 for about six years and had fantastic luck. I usually buy enough oil to last all year and it's about time to start the season. I guess the reason I ask this question is because I'm hearing some good things about the Brad Penn oil and with the changing of the automotive oils I want to be sure the SM/CF is adequate for my application. I have a Puller so heat is not an issue, infact lack of oil temp. would probably be a bigger concern. Alcohol for fuel, aluminum block and rods and if memory serves .0035 clearance on the rods, no gear drive, the overhead is drilled for oil, and the oil is changed every two to three passes. Thoughts on the best oil for my application would be appreciated, thanks.