Does anyone know the difference between marine gear lube and automotive gear lube? Both of these I'm looking at are the same brand, same rated viscosity, and are both GL-5 rated. The marine version is about a buck more per quart.
I've used both, mostly depending on availability. I've heard the marine lube is supposed to separate from water better, but if you have water in your lower unit.... you still have water where the lube is supposed to be.
Exactly. More specifically, it's designed to retain its ability to lubricate and protect against corrosion even when contaminated by water. I use the Amsoil lube, which continues to work even under 10% water contamination.
Using an automotive gear lube will not kill anything, but if any water gets past the seals, it'll break down fast.
Originally Posted By: garyb80
Does anyone know the difference between marine gear lube and automotive gear lube? Both of these I'm looking at are the same brand, same rated viscosity, and are both GL-5 rated. The marine version is about a buck more per quart.
Marine Gear Lubes have a bit more of the following:
Emulsifiers
Corrosion inhibitors
Rust Inhibitors.
So the cost is higher because the addpack is more expensive.
Unless you are covering your diffy with water by crossing streams or such you don't need it.
i know the quicksilver/mercruiser high performance gear oils (the blue one) have small amounts of moly in it. the original bob (BITOG#1) discovered it in UOA about the time i joined this club:
I said "often"...that is why majority of outboard gearbox oils are GL4 rated...
but nevertheless...you can still pour in oils with GL4+ or GL4/5 or GL5 + MT-1 ratings without harm to bearings (different chemistry...same protection level as GL5...)
Originally Posted By: hattaresguy
They just get to charge more.
Water in a gear box will wipe it out very quickly, don't care what oil is inside.
And you make a good point.
If you're submerging your diffy either by crossing streams or by backing a boat into the lake frequently, you should be changing the diffy lube after such an event.