I will repeat this, just to be sure there is no misunderstanding, and to AMEN what Phil and Scott posted behind me.The Mercury XS engines, the 250 XS racing motor, and the 250 and 225 Pro XS engines, all are designed to be run on the Mercury Premium Plus Oil. Mercury DOES NOT recommend the DFI oil for these engines. As I said in my first post, I want told, point blank, NOT to run DFI oil in these engines. This was from a tech rep at Fond Du Lac.Out of warranty, run what you want. In warranty, Im running the oil that Merc recommends. One more thing in my favor if I ever do need a warranty claim.Mike Whitten