Gear Oil

[okiemark]

I put Rotella HD in mine. It is the same stuff I use in my tractors. I looked up in the specs and it is non corrosive to copper and brass.

[LarrBeard]

I put Rotella HD in mine. It is the same stuff I use in my tractors. I looked up in the specs and it is non corrosive to copper and brass.

This ties back to BMorgil's comment about million-mile super heavy duty gearboxes using straight 40W oil. No sulfur based additives, therefore no brass issues. But 40W and Rotella seem to be one of the lesser known secrets - probably because there isn't a lot of glamour or magic to them - they just get into things and work.

[bmorgil]

Very true. Not many people realized that the big truck fleets of the day learned that one motor oil would do a lot. It definitely reduced their inventory of maintenance items.

The thing to remember is there are MANY combinations of additives in lubricants for MANY different reasons. What we know as an Extreme Pressure Additive, is something designed with sliding friction involved. All lubricants must maintain film strength in a given situation. In motor oil these additives that protect and maintain strength are referred to as Friction Modifiers. Combinations of this stuff make up lubricants for different applications. A good example is Rotella. A motor oil that will perform in a transmission with synchronizers indicates the correct lubricity. If it were an EP, the syncros would have difficulty because of the EP additive. Even if it had an EP that was compatible with brass, it still would have the wrong properties. Again Rotella does not contain EP as we think of it. Rotella also has Friction Modifiers that make it compatible with the clutch facings in the auto trans axles and the brakes that are submerged in some cases.

It comes down to economy. You don't need the high detergent of a motor oil, but it doesn't hurt. You don't need Friction Modifiers for facing materials, but it doesn't hurt. The most important things are the correct viscosity, additives and compatibility with the internal components. Sometimes you can find something that though it has more than you need, it is cheaper because of how much of it is available.

Finally if you are looking for something that is application specific, you are going to pay more for it. I don't know what to think about that. The Red Line is made specifically for the trans. I do know how it performs "under the gun". Would a good motor oil do just as well? Probably! It just comes down to what you want to trust or, like.