Bought some Mercury brand 25W50 synthetic blend engine oil for oil change. The container says high performance marine applications. My thought is, if this is formulated for HP engines, it should be even more effective with my Crusader 5.7 XL, and offer a high degree of lubrication. I run the engines at 3000 to 3100 RPM most of the time. Talked to a Mercury "certified" mechanic about that oil. His reaction was he would not recommend using this product because it is formulated for Mercury Verado engines only. He said something about an "impact" performance condition, that may negatively affect my Crusaders. Guess I can still exchange for a better suited product, but not convinced I should. VIPER - what do you think? er