Well they all meet the same international standard - TCW3, which is usually all the engine maker specifies (unless you have an Etec with special desires!).
Since mercury / yamaha etc don't own any oil refineries they are just relabelling it. If they were adding special additives there would be marketing claims splashed across the bottle.
Poly, I have a Etec, but I have the special desire,,not to fook up the engine !!
Simple really. so any TCW3 derivative is ok ?
I'm more of a simple tech person. Presumably you have the engine set for TCW3 already. There are some super fancy (i.e. expensive) etec oils around - but if your engine is set for them you shouldn't use bog standard TCW3 - as I understand it.
As long as the engine is NOT set to use XD100, then any TCW3 oil is fine.
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