porphyry

I just bought a very nice rebuilt AX15 from a good reputable transmission shop down in Denver. On the receipt, the shop master wrote fill with 10w-30. Now, I know how to use the search function, and I don't plan on getting into a debate regarding the use of 10w30 vs 75w90 GL4. I plan on running Amsoil MTG 75w90 GL4.

All that being said, my question is how should I break in my new transmission? I figure that I should drive it easy for a thousand miles and let the synchros set. Should I change the fluid after a thousand miles? Should I run a different fluid and then switch to the 75w90? If it makes a difference, I live in the high Rockies, and our temperatures are around 80 for the high right now and through the summer, 40 for a low. During the winters, it will get down to -35 for a couple of days, with highs around -10. Usually during the winters, we see lows of around -15 or so, with a high around 5 or 10. I have a 4.0L HO driving it, with an NP231 behind it.

Any thoughts? Thanks in advance!

porphyry

Additionally, I changed the fluid on my current transmission about 400 miles ago. I put Amsoil Severe Gear 75w90 in it with the thought of trying to squeeze a few hundred more miles out of my tranny until I could better afford a new transmission. That obviously didn't work, but I don't want to simply toss $60 worth of excellent GL5 gear oil. Should I try to salvage it and perhaps throw it in my diffs? Any thoughts on how to accomplish that? Thanks!

lk123

I just had mine rebuilt and looked forever on types of fluid but coulnt afford or find gl4 around my town so ended up going with mobile 1 syn 1030. I ran it for the winter i dont drive much but home and work and it did fine then changed it and its doing great. Wish i had a auto though lol

Gee oh Dee

I plan to run synthetic 10w30. I am swapping in a trans right now.

porphyry

Interesting. I know that you know your stuff, so perhaps I will run 10w30 for a couple thousand miles, let the synchros seat, and then switch to the Amsoil.

DFlintstone

You might consider one of those little pumps that work with a drill? Also you could siphon it, but I'd plan on it taking overnight...maybe!

I also found if you lay it on it's side in the back seat of a Tempo, all the oil will run out.

partsguyct

Yeah but that's only because fords attract fluid leaks lol

porphyry

Fluid already looked like crap. Oh well. I'm sure it had a use, but I'll leave that for the idiots at Wally World to figure out now. Transmission is in, found and fixed two other problems, hopefully it will run good tomorrow when I throw the exhaust back in and give it an oil change while I'm down there.

salad

Owners manual has nothing transmission-specific WRT breakin, just the engine stuff. Hard to tell if it doesn't need it or if the engine breakin period also breaks in the tranny. Then again I've never heard of anyone breaking in an AX15 before, its not like there are rings to seat or cams to condition.

And do yourself a favor and stick with the Amsoil MTG. Engine oil is NOT gear oil, it would be unfortunate to see a newly rebuilt get treated improperly.

porphyry

Definitely sticking with the Amsoil MTG (no offense to the 10w30 opinion holders out there). I'm pretty excited about using it and seeing the difference between Amsoil SVG GL5 and the Amsoil MTG GL4. It should run extremely well now. I'm about to put the oil in and try her out.

salad

Nice! Yeah you should see a big difference between an oil that eats brass synchros vs one that that actually works with them properly. Did you buy it rebuilt from some shop?

porphyry

I bought it from A1 Transmissions in Denver. They've been great to me in the past. Great price, and quality products. Would've loved to do the rebuild myself, but I don't have a 7 ton hydraulic shop press. I have a 3 ton arbor press, but it doesn't have enough clearance to press gears onto those huge main and counter shafts. Bummer.

Gee oh Dee

So this reputable transmission shop suggests 10w30 and you come to a place that requires no education or background at all and ask for our advise?

salad

Hmm indeed! I don't remember reading the first part of the first post lol

I would love to hear the shop master's explanation on why 10w30 is recommended

porphyry

I just assumed that it was because of the Chrysler TSB. I know that's what Chrysler wants you to put in it, I know plenty of people use it and it works just fine, but I've read plenty on lubrication over at BobIsTheOilGuy and I would prefer to use 75w90 GL4. My questions were regarding breaking in the new transmission. I'm pretty confident as to my lubrication choice.