Home › Forum › Ask A Member › 1958 Sportwin Lower Unit Oil Question › Re: 1958 Sportwin Lower Unit Oil Question
I certainly won’t argue with Fleetwin here. It’s probably wise to use the best marine gearcase oil you can buy in the 4-bolt OMC gearcase on a 10 hp. I personally just use bulk GL-5 90W gear oil in mine. I do look to find something that says it is safe for use with yellow metals. I’m aware of the weakness of the 4-bolt 10 horse OMCs and I check them for water often and keep good seals in them. My motors don’t get left in the water either. I tilt them up when I dock or moor the boat. If you only change the gear oil once a year and leave the motor down all the time, I recommend something that has the additives in it that help maintain lubricity with some water present.
-Ben
OldJohnnyRude on YouTube