80w-90 Gl-5

[Kenneth F.]

Is this choice of gear oil acceptable for a B/W T-10? If not what should be used?

Thanks,

Ken

[Jim D.]

Re: 80w-90 Gl-5

That will be just fine. Go a head and use it.

[Duke W.]

Re: 80w-90 Gl-5

The original spec was Mil-L-2105. This spec was cancelled about the decade ago and the military now uses the API equivalent spec which is SAE 80W-90 GL-5, so that's what you should use.

Brand doesn't matter. Like engine oil, buy gear oil by API spec.

Duke

[Eric D.]

Re: 80w-90 Gl-5

You need GL-4 gear lube, the GL-5 has the friction modifier for use with POSI rear ends,
which is the same additive that makes the sycro rings not work...
Hope this helps... Eric

[Dick W.]

Re: 80w-90 Gl-5

GL-5 will work fine with synchronized transmissions

[Duke W.]

Re: 80w-90 Gl-5

You need GL-4 gear lube, the GL-5 has the friction modifier for use with POSI rear ends,
which is the same additive that makes the sycro rings not work...
Hope this helps... Eric

No, 80W-90 GL-5 DOES NOT have the Positraction additive, It is the modern equivalent of Mil-L-2105 that GM specified for all these old manual transmissions when they were manufactured in the sixties and seventies. Mil-L-2105/80W-90 GL-5 is also the correct lubricant for open hypoid axles.

Positraction axles require the addition of a "friction modifier" additive to common 80W-90 GL-5 to avoid clutch chatter (stick-slip friction), and it is the same additive that is included in all ATFs since all automatics have wet clutches.

I have seen some commercial 80W-90 GL-5 packages that state "suitable for limited slip differentials", but that doesn't mean it has the additive.

The only axle oil I know of that has the Positraction additive included in the product is Redline 75W-90. They also offer the base oil without the Positraction additive that is called 75W-90NS.

Duke

[Kenneth F.]

Re: 80w-90 Gl-5

Thanks to everyone for this interesting much appreciated information.

Ken