Need for GL 1 Gear Oil in Old Machines

[Langanobob]

I've understood for years that GL-5 gear oils may have additives that are damaging to copper alloys found in transmission synchromesh parts and in bushings and that GL-1, 2, 3 and 4 are safe for older machines that may have copper parts.

However, recently I've run across old tractor owners who claim that only GL-1 is safe to use and that in addition to GL-5, GL-2, 3, and 4 can also be corrosive to copper alloys.

Is this correct?

Thanks,

Bob

 

[Johnny]

In some instances, yes. Just depends on what the application is and how old it is. You can still purchase GL-1 gear oils, but they are hard to find. It's the EP additives, mostly sulphur, in the GL-5 gear oils that attack the soft, yellow metals.

 

[Langanobob]

I probably should have worded my question better. I know that the EP additives in GL-5 oils can attack yellow metals. Some people claim that the additives in GL-4, GL-3, and GL-2 also attack yellow metals and you need to use GL-1 in any machine containing soft yellow metals. My question is: Do GL-2, GL-3 and GL-4 rated gear oils also attack soft yellow metals?

Thanks,

Bob

 

[Johnny]

I've never known of GL-2 or 3 attacking soft metals, but I have heard of GL-4 attacking in some older stationary gear boxes. Most manual transmissions in older European cars can handle GL-4 without any problem. If I had and application that called for GL-1 I would use it. I believe both GL-2 and 3 specs are obsolete and were replaced by GL-4.

 

[tom slick]

I'd look into industrial gear oils instead of automotive/farm/heavy equipment oils. Many industrial gearboxes still use yellow metals, especially worm-drive speed reducers.

 

[Johnny]

Good idea Tom.

 

[mechtech2]

GL4 is not void of GL5's yellow metal corrosion additives.
It has about 1/2. So it's better, not free of them.

Many GL4s are safe, either buffered, or a new technology. But so are many GL5s.

 

[Johnny]

True.

 

[edhackett]

There are GL5 lubes that are perfectly suitable for GL1 applications. Chevron Delo Gear Lube ESI being the best example. It does not contain sulfur based EP additives.

Ed

 

[bruce381]

while the borate system works well it is my understanding that shock loads were a concern and as such S/P are still used at a smaller level.

 

[Kestas]

Doesn't operating temperature play a factor in determining whether an oil application is safe for yellow metals?

 

[unDummy]

Yes Kestas, anything pushed to the limit will have an issues. Temperature is one of many variables.

Everything can be corrosive is run too long, if run too hot, and if moisture is an issue.

I could care less about the internet fear and hearsay.

If you can't keep the gearbox at a safe temp, can't keep the water out, and don't want to maintain it, then by all means find the GL1 gear oil.

 

[bruce381]

normal acid formation in an oils will increase copper corrosion rates so I agreee