I wrote to Mobil to see if there is anything to this rumor that GL-5 gear oil is bad for AX-15 transmissions. Here is their reply:

 

We have nothing for you.

Hope this helps.

??

 

What to use:
https://www.redlineoil.com/mt-90-75w90-gl-4-gear-oil

 

My AX15 LOVES the Redline MT90. Just as pricey as the Mobil 1 but considering I use the Mobil1 motor oil, I'd be paying that much anyway.

 

Was looking on their website for dealers near me. I think "Regular Cars Guy" from YouTube must be their content input operator. They call "Advance Auto" "Advanced Auto" in every instance, and they don't carry Red Line oil anyway. They carry the whole array of not-gear-oil, including friction modifier.

O'Reilly, they have MT-85, not MT-90.

On the Red Line website, direct from them, the only shipping choice is FedEx 3 day. BTW, getting a gallon instead of 4 quarts is more expensive. Total price: $90.94. But I haven't run the site through Honey yet.

Edit: However, some outfit called HRP sells it on Amazon for $60/gallon. It gets over the Amazon free shipping hurdle and with tax where I live the total is $66.63, before checking for other discounts with Honey.

 

Did your AX15 slip you a little love note to let you know?.....lol

 

Looks like my standard gear oil pump from harbor freight doesn't screw onto the top of a gallon jug. More mods in store.

 

Anyone else here with a factory Dana 35 LSD rear?..... what additive seems to be best for the LSD when putting in fresh gear oil?
Not really thread jacking as it's right along the same line as the OP

 

OMG always thread jacking everyone Rocket..... Don't make me tell a mod

 

LOL....it was right on the same line of conversation you meanie....
It's not like I started talking about Event Horizons, Quantum Physics, and String Theory....

 

What kinda weirdo would have one of those? Chrysler 8.25 baby!

BTW, my followup to Mobil was if I need to use limited slip additive to Mobil1 75W-90 and they have yet to respond.

 

Pennzoil syncromesh is what I always run in the AX15. Works great, cheap and readily available.

 

I put a gallon of 15w40 diesel oil in mine, same oil I use in the engine and it shifts great.

 

Many folks have also sworn by Mobil 1 engine oil, either 5w30 or 10w-30. I ran 50/50 MT and MT90 when I had a manual. NAPA house branded GL3 shifted horribly.

 

Well just to jump in on the convo. I am currently doing a flush on my whole vehicle cause everything is getting restored (to my best abilities and time strains). I added some atf to my mt-90 to clean things up in the tranny cause I doubt the fluid has ever been changed. Lets hope I didn't **** something up by doing that XD. I'm running all my fluids for 500 miles and then changing them all so hopefully everything is buttery smooth.