I currently have the gear lube in my transmission. The stuff is really thick going in when cold. The 5-speed shifts much better when it has 'warmed' up. I saw the 'gear demo' on the parts counter with the additive vs. regular oil and thought that it would protect 5th gear. I don't tow anything worth mentioning but the tranmission definitely shifts better.
Matt
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90 3/4 ton, 4x4, 5-speed, 3. 54 gears.