Does it make the shifts smoother then conventional? And other then that what other results has it shown?

Just got off of the phone with Royal Purple and it turns out that the Syncromax Trasnmission Fluid has a very light viscocity rating, Close engine oil, Like 10W-30. I was informed for the AX series transmission you want to use the 75W-90 Gear oil if you have the manual transmission in your cherokee.

Does RP offer a yellow metal safe gear lube???

Redline MTL, MT-90 and Amsoil MTG are all yellow metal safe gear lubes intended for manual trannies requiring gear lube.

Not a clue, I asked the guy If this gear oil was safe to run and if it wouldnt damage my syncro's and never really got a strait forward answer, he just told me that that was what was recommended by the manufacturer. Im just trying to get some gear oil/tranny fluid thats going to last and help keep wear down on all of the parts, Seems like its alot harder to find then it should be.

code for he didnt know

Exactly, So I have no clue if its safe to run or not. It dosent even say if its safe for yellow metal in the description, just that you can run it in diffs and transmissions.

Hmmm, I can email the head of the tech department. Do you know who you talked to?

Not a clue, he didnt give his name

http://www.royalpurple.com/prod-pdfs/max-gear-ps.pdf

well.. its says its a GL-5 lube.. which means too much sulfur for yellow metal gears. But they also claim on that sheet that is passes some proprietary wear test on bronze gears...

So what is this wear test... and how many cycles does it simulate. Because the damage done by sulfur to the gears is not instantaneous, but it accumulates over time.

So basically running royal purple in the AX-15 is a no. I plan on keeping this cherokee for a LONG time so Royal purple is out. But Amsoil and Redline MT-90 are good enough to run without any real long term wear other then regular wear of the gears coming together and wearing down over time?

I'll search my contacts for this guy's email and report back.

Here you go;

Josh,

For the AX-15’s the call for an SAE 75W90 API GL3 rated oil, Royal Purple recommends using the RP SAE 10W40 Motor Oils.
An API GL3 oil does not contain any EP additives – so using a GL4 or GL5 rated oil is a miss application.

The RP MaxGear 75W90 will not harm the bronze synchronizers as it uses an inert synthetic EP additive package but it is an EP gear oil and is the incorrect type of fluid per the OEM recommendation. Unfortunately the OEM in this case has flip flopped on the type of oil recommendation on this particular application so it really is a warranty issue.

I have been with RP for 18 plus years and have not seen our MaxGear cause any corrosion in a manual transmission with bronze synchronizers.

This forum debate is a common thread on the internet – as many uninformed car enthusiasts think that this is a black and white issue when it really is not.

Cheers,

David

Interesting.

I'm curious how they would measure the corrosion, and how long they immerse the bronze article in the oil

I used Synchromesh is my tranny and it worked fine. Mopar's new spec is no longer GL3 gear oil...it's simply 10W30 motor oil. Right on quadratech http://www.quadratec.com/products/52250_90.htm . I steered clear of the motor oil, but some people said they've used it with no problems.

Redline MTL for the win, won't run anything else.