I used BM for a few years with wonderful success, really liked the oil and seemed to run well in my sled. Then the motor seized on me, which also caused me to loose the crank. Figured it was just time for the 05 Skidoo Summit 600HO to loose a ring. Bought a new motor over the summer and waiting for it to be returned. I then read a post from Kelsey, at RKTEK (who had been using blue marble also), and he stated that he has been noticing a large buildup of carbon from the new batch of oil coming from Blue Marble, which was causing the rings to not to fit properly. I got my sled back, kept running the blue marble, seized the motor again after a couple hundred miles, the dealer had no explanation as to why it seized. He replaced the piston and cylinder, and I changed oil. Ran the sled all last year with no problems with the new oil. That is my experience.