Originally Posted by Mercury
Can anyone tell me if the Two stroke oil used in motor bikes & lawnmowers is the same as used in outboard engines? And if not will it do any harm if it is used. cheers.
It is NOT the same, and should NOT be used.
Bikes, lawn mowers etc are air cooled and so run much hotter than a water cooled outboard (which almost all are, and certainly any recent reasonably sized one). The result is that your engine will not be properly lubed - prolonged use is likely to be bad, potentially terminal, and short use is likely to result in fouling of plugs etc.
2 stroke outboards use TCW3 grade oil, unless you've got some fance modern direct injection (e.g. Etec) engine which will be even more sensitive to using the wrong oil.