I’ve never had any experience with it in an outboard, but I can tell you that the manual for my Dodge truck says that for trailer towing the rear axle gear oil should be drained and replaced with synthetic. So I guess that means Chrysler feels it is better for wear prevention. Works for me, we’ve towed the trailer to Alaska, plus across the 48 four times, plus more.
fleetwin US Member - 2 Years Replies: 4737 Topics: 46
Well, kinda hard to say, depends on what oil you are referring to when you say "synthetic". The Merc/OMC partially synthetic lubes do claim to be better and absorbing a little water to minimize wear.
What gearcase are we talking about here? Some are more tolerant to water than others.