Which one? I have always used the M1. Before I got on here, I was one of those guys that wouldn't touch a Fram filter. Obviously Ultras are very respected on here. Ultra is cheaper by a few dollars. It will be going on a 2015 Polaris RZR 900. Oil and filter gets changed every spring. Usually about 1,000 miles on OCI. Oil will be M1 15-50, two quart capacity. Warm weather use mainly. Sits in heated garage in winter if I needed to use it. What say you? They about the same quality wise? Thanks!