The "recommended oil" issue seems to hang around and cause some angst, considering the warranty problems if a super charger or motor goes south, and Bombardier claims that the wrong lubricant was used. Superchargers with ceramic plates are supposed to use semi-syn in the 10w40 weight. Newer boats (2010 up) may benefit from use of full-syn, even though they are supercharged (RXT 215). Dealerships now carry the factory endorsed full-syn in the yellow bottle, which claims to be THE OIL for all things Bombardier, supercharged or not. This is what I have used on my 2010 RXT 215, and have had no supercharger problems YET. I will stick with the full-syn for another season. I will winterize both my boats next weekend, and refill with full-syn unless someone has other info I am not privy too.