I had run amsoil until this year. I put a built shortblock in my car last year and noticed some build up in the oil pan. My friend Tim that runs an 8 second mustang on e85 noticed the build up also using Driven full synthetic oil. Talking with other racers he switched to driven GP-1 last year and when he took the pan off at the end of the season he didn't have the build up, looked new. So this year I'm running the GP-1.
Now if I was not running e85 I would still be using Amsoil 0-40