Re: force 120 outboard
80-90 weight is the stuff that you use. Some are marked 85 weight, and the stuff I buy at Wal Mart (Lubri-Matic synthetic) is not marked at all.
If all you can get is automotive rear end lube, it will work, but Marine lower unit lube is preferable because it has more corrosion inhibiting additives--better to prevent rust if water gets into the unit.
