Trans fluid

I'm sorry, but I'm new and don't know where the tech archive is and I'm assuming I might be able to find the answer to this question there.

But anyways, I read an old post about Manual trans fluid(GL-3, -4 vs. GL-5)

I want to now if I buy the redline mt-90 if I could or should use the Lucas treatment.

I have used Lucas in the past in my trans and have been happy, but reading about the stuff they put in the GL-5. I am worried that the same stuff is in the Lucas.

Any advice would be helpful. thanks

made a Rook mistake
I have an AX15

Damn it

89 XJ 4WD

So whats wrong w/ using a better GL5 fluid in the trans that doesn't need any extra additives added to it? It does take a 75W-90 gear oil right? Get full synthetic Severe Gear from Amsoil and never worry about adding anything to it.

The GL-5 recommendation in the Owner's Manuals for a couple of years was a MISTAKE. The trans requires GL-3 Fluid, GL-4 and GL-5 contain additives that become corrosive to the Synchros if it gets too hot. Some people have reported damage and shifting problems when they've used GL-5.

Using a Fluid with friction modifiers will make the shifting smoother and easier, it helps the synchros a lot. Regular Gear Oil does NOT have Friction Modifiers. Most "Manual Transmission Fluids" do have the Friction Modifiers.

Many people have been using Redline MT90 in their AX-15 and AX-5 and notice improved shifting. It has the friction modifiers, its also synthetic fluid. BUT, its GL-4 fluid, but the literature for the fluid says the synthetic formulation prevents the additives from becoming corrosive to the synchros at twice the temp that other GL-4 fluids do. No one has reported a problem yet, using the MT-90.