hi all <br /><br />I have recentley been given a 10 hp merc ..age unknown .. it fires up first time and runs well for about 15 minutes and then gradually loses power and dies could it be a heating over heating problem , it has apparently been run with engine oil as a mix instead of 2 stroke could this be a problem
<br /><br />It does sound like your engine is overheating. That is more likely to be caused by a failed/failing waterpump than wrong oil, but wrong oil mixed too lean could also cause overheating.<br /><br />First, replace the water pump impeller. Then decarbonize the engine (see the FAQ section for a good article on decarb) to clear out any deposits left by the motor oil.<br /><br />Use TC-W3 outboard oil at 20cc/liter of unleaded regular gasoline. I think regular is rated 91 octane by your system.<br /><br />Good luck.