Originally Posted by Hydrocruiser

After going around in circles on marine gear lube I don't think you can do better than Mobil-1 75w-90. The only thing it dosen't have is the word "marine" on the package.

Originally Posted by Rebel_Heart

How is the Mobil 75w-90 different than the Amsoil products? Are you able to purchase the Mobil product in local stores?

Originally Posted by Hydrocruiser

bad seals typically are what cause premature drive failures.

Originally Posted by Hydrocruiser

Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures.

The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance. In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.

Fortunately, today's synthetic oil and additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.

This means not all synthetic oils perform alike and the same goes for conventional oil too.

Originally Posted by Rage

Where does Red Line Shock Proof Gear Lube 'Heavy' weight rate for the Bravo X drive versus the others mentioned?

Originally Posted by Wobble

From their website

"Heavy ShockProof™

A unique lubricant containing a suspension of solid microscopic particles as an extreme pressure agent--unique solid dispersion which cushions gear teeth to help prevent tooth breakage and allows the use of lower viscosities. Recommended for heavily-loaded racing differentials and transmissions, Off Road racing and problem gearboxes. The viscosity characteristics allow the lubricant to resist throwoff and provide a film thickness similar to a 75W250 grade, while providing the same low fluid friction as an SAE 75W90. "

Probably the ultimate gearlube, I found it to be messy, hard to find and very slow to drain. Ended up switching to M-1 75/90 as it is readily available

Originally Posted by cloudmaster_321

I guess i don't quite understand the theory on the changing oil weights. I just know for example, i run the 5W-30 in my truck in the winter because the 5w is thinner and will circulate the motor better on cold starts vs. say a 10w-30. But the 30 weight is a thicker weight, but when oil is hot, it isn't thicker, it's thin? Do you know what i mean?

Originally Posted by cuda

That is a very true statement. I think for 99% of us, Merc dino lube is fine. Drives don't last long when they are lubricated with seawater.

Originally Posted by Hydrocruiser

If somebody can develope a device to monitor the drives for water... with a very load ALARM attached to the dash board you could probably make a lot of $$.