Tim, I have to respectfully disagree with the recommendation of using GL-5 fluids for transmissions. The added Sulphur needed to make the GL-5 rating is generally corrosive to synchronizers, and any brass/bronze components, and not needed for other than hypoid rear ends and similar. A good GL-4 fluid is sufficient and synchronizer friendly. Further, fluids that are properly designed for transmission use have the right characteristics that promote smooth shifts. A typical GL-5 gear lube that is great for rear ends doesn't necessarily meet that, either.
Now, I'm not pushing the brand, as there are many choices, but here is a good white paper on the subject, FYI.
Red Line MTL and MT-90 Tech Info.
Cheers!
Doug
