I have a 1991 Four Winns with a 5.7L engine and OMC I/O. I'm the 3rd owner and only have 320 hrs on it, 210 of which I put on it. The closest boat dealer is a 250 mile RT so I called NAPA, meaning to buy some Sierra Outdrive lube with a GL-5 rating per the manual. They had some Mercruiser...
