swapping all fluids, double check my choices

So I am picking up all the fluids and hopefully swapping everything tomorrow evening. Insurance agent is taking care of my registration and insurance tomorrow and will have me the plates on Thurs so after 18 months I think I will swap out everything before putting any miles on the rig.

I know this has been answered a million times, I just want to double check my choices.

Gear oil: 80w90. Or maybe synth 75w140. I probably will end up running the autozone special cheapo brand since I will [hopefully] be swapping axles/gears soon anyway.. well, running the cheap s*** unless anyone has horror stories of that stuff killing gears :laugh:

T-case: IIRC, it uses ATF+4? I don't want to run any expensive brand since A) my case leaks a bit and B) I will be picking up an SYE sooner or later and will need to drain it anyway. Dont plan on pushing the case too hard until then.

Trans (ax-15): GL-3 trans fluid. Or synth mobile 1 10W30 maybe? I heard the motor oil can be used but want to check if anyone destroyed their ax-15 by running it before I do so.

(Trans fluid is actually why I am doing the full fluid swap... I installed a new clutch about 8 months before I took the Jeep off the road and quite frankly idk what type of fluid I re-filled the tranny with. If the haynes called for GL-3 then chances are that is what I used... but idk for sure so it is getting swapped. The little that I did drive it she still shifts OK, so hopefully no bad damage has been done.)

TIA

-Scott

I have an ax-15. I changed what i'm assuming was the factory fill (bought it used) at 130k miles. Changed it with regular dino 10w-30 engine oil. noticed ZERO difference, NOTHING changed at all. ran that for awhile, then had to do the clutch and replaced some tranny seals, so i drained the fluid, and replaced....but this time with synthetic 10w-30. THe difference i felt immediately. best way i can describe it, is the difference between an ice cold manual tranny and one that has warmed up a bit. you know how colder manual trannys are a bit stiffer ect. well w. the synthetic even when the truck was sitting over night, the tranny felt as if it was already warmed up a good bit. Noticeable difference, especially in the cold weather, a lot less stiff in the morn.

I did not use mobil 1. both times were with walmarts house brand 'super tech' never had an issue w/ any of their lubricants, infact thats the engine oil i've been using the past 20k miles w/o issue.

My np 231 i run regular cheap ATF no problems.

Banditt007 said:

I have an ax-15. I changed what i'm assuming was the factory fill (bought it used) at 130k miles. Changed it with regular dino 10w-30 engine oil. noticed ZERO difference, NOTHING changed at all. ran that for awhile, then had to do the clutch and replaced some tranny seals, so i drained the fluid, and replaced....but this time with synthetic 10w-30. THe difference i felt immediately. best way i can describe it, is the difference between an ice cold manual tranny and one that has warmed up a bit. you know how colder manual trannys are a bit stiffer ect. well w. the synthetic even when the truck was sitting over night, the tranny felt as if it was already warmed up a good bit. Noticeable difference, especially in the cold weather, a lot less stiff in the morn.

I did not use mobil 1. both times were with walmarts house brand 'super tech' never had an issue w/ any of their lubricants, infact thats the engine oil i've been using the past 20k miles w/o issue.

My np 231 i run regular cheap ATF no problems.

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Well then, Synthetic oil it is. Maybe I wont spend the extra money on the mobile 1... maybe I will. Not sure yet. Thanks for the info.

The 231 takes Dexron III, but it's not as picky as the AW4 about which brand or whether on not it's synthetic. I think some people have reported slow leaks around the seals when using syntetic though.

I run Redline MTL in my AX-15. When I first put this in there was a definite difference in how the tranny shifted. The shifting smoothed out.
Also, in cold temps (when I still lived up North) the shifter still works good.

I use Quaker State ATF in the transfer case.

Put regular gear oil in the diffs. I change this out everytime I go thru water which is over the hubs or about every 10K miles.

Gear oil - whatever is cheapest and certified at autismzone when I show up.
tcase - dexIII/merc ATF as others said, it's really not that picky

Oh yeah, I forgot about the Dexron lll. I remember that's what I am running now. I probably would have remembered that once I saw it on the shelf :gee:

For trans: maybe I will pick up some redline MTL if I can find it for a reasonable price. If not, then engine oil it is (though engine oil seems a bit thin for the ax-15... doesn't the ax-15 specify a much heavier oil?)

Other question is: It wouldn't hurt to get a small quantity of (for example) Redline MTL in the T-case, would it? I am probably picking up some type of pump to make filling the cases easier... so if there is some residual trans fluid in the pump it when I fill the t-case (or vice versa) it wouldn't do any damage, right? I will probably fill the trans first, then move onto the t-case. Only because the trans has the yellow metals and idk what the dexron would do to them.

Then it's just a matter of whether or not t-case fluid would hurt the differentials at all (if I even need to use the pump for the diff's, I doubt I will).

Thanks for the checks.
-Scott

I've read that the AX-15 love the Pennzoil Sychromesh gear lube. I read that they're hard to find but I found a bunch of them stocked on shelf at my local Advance Auto Parts. They're most preferred because they're made right for the AX-15's synchros metals

for the np-231, I just run some regular cheap ass Coastal auto transmission fluid, but if its my daily driver I might would want to run some synethic for a little better protection and MPG.

for the axles, it dont really bother me on whats the difference between 80w-90 or 75w-90, normally there's only one of them in some store, no big deal.

if your axles have proper level of gear lube, leave it, not change it. because you said you will have new gears installed in near future so why waste your $$? same thing for the transfer-case. Just make sure they're at proper level and run it til you get new gears and SYE installed then run fluids that you want in it

95' heep said:

if your axles have proper level of gear lube, leave it, not change it. because you said you will have new gears installed in near future so why waste your $$? same thing for the transfer-case. Just make sure they're at proper level and run it til you get new gears and SYE installed then run fluids that you want in it

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I haven't checked the diffs in a while (since I swapped out my rear axle when I killed my first one, that was probably 20-30k miles ago). Also, just before I took it off the road I beat on it a bit and I want to make sure the fluids are all nice and I want to check the gears anyway to be sure everything is still looking OK. So cracking the diffs just makes sense, $10 per axle to be sure it's all good is OK in my book.

I am also concerned I may have tore off my breather(s) somewhere along the line. I am mostly concerned about my trans because I feel like I recall that as I was installing/plugging in the trans, something snapping off and me saying "meh, too bad, f*** it". It was just as I finished getting the trans installed after doing a clutch, at 9PM at night, on a sunday night... and I still had to clean the garage, clean myself, re-install my interior pieces, and drive 1.5-2 hours back to college so I was there for an 8AM exam the next day... needless to say a breather wasn't on the top of my concerns list. It was already broken, so I couldn't fix it anyway :laugh:

But yeah, I just want to start fresh, I wouldn't doubt my t-case is pretty dry since it was leaking when I put it away. And I trans I want to do incase I didn't use GL-3. so that covers everything :thumbup:

So yeah, the guy at Advanced spent 10 min trying to convince me I needed GL-5 because thats what the factory spec said...

So just out of curiosity: If a fluid is listed GL-3, GL-4, GL-5 does that mean it meets GL-3 specs and is safe for the tranny? Or does the fact that it is also rated for GL-5 mean that it is not safe for the tranny? I went with Mobile1 10W-30; more just out of curiosity for the next time around incase I don't like the mobile1 for some reason. :dunno:

Most fluids that are rated higher are good for any previous. Depending on the component, and age it can affect it, sometimes there is more (or less) stuff added into the mix that could not be good for a particular item. As far as manual trans and axles go, I see no issue.

as I recall some GL-5s will corrode synchros. If they are listed as yellow metal compatible they will be fine.

I don't have a manual though, so anything I know about them is info absorbed via osmosis, and can be anything from correct to a beautiful work of fiction.

kastein said:

as I recall some GL-5s will corrode synchros. If they are listed as yellow metal compatible they will be fine.

I don't have a manual though, so anything I know about them is info absorbed via osmosis, and can be anything from correct to a beautiful work of fiction.

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As long as it's beautiful.

I don't want no fugly fiction anywhere around my Jeep!

even you want to "check " your differentials I still say no if you dont have any problem with them. many dont have problem running with few broken teeths and you are going to have new gears in there soon anyway.

again, what I read on here, using Pennzoil's "synchromesh" for the AX-15 is highly recommended. otherwise any oil is better than nothing.

for the t-case, again make sure its topped off then you're good to go til you go SYE then put in some $$$$$$$$$$ synethic oil in it.

Do not put GL5 in an AX-15. That fluid will destroy it (ask me how I know). Jeep manuals said to use GL5 for a while. That is wrong. Jeep corrected it but never admitted to any error.

My AX15 went out at 37K miles. At 15K miles I changed the fluid using the recommended GL5. Boy was that a costly mistake.

And while you are at it I would change blake fluid and cluch fluid too.You will be suprised at the diffrance in brakes a flush will do.I do mine alease once ayr brake fulid will mix with water thats one thing and it will then boil if you get your brakes hot and then you end up with small air pockets in it and brake fluid dose break down just like any fluid dose. besides the water will couse rust in your system wheel cyl and brake cal. .Same with the cluch fluid water will rust the lines and the slave cyl the master cyl is alum but it will miss it up to .I use dot 4 fulid

Already cycled clutch fluid (I didnt do full flush though, that is coming next). Brakes were on the list, I just remembered I have some fluid from when I topped my car off a month or 2 ago. Will cycle whatever is in my master cyl out with the fresh(er) stuff. Thanks

kastein said:

as I recall some GL-5s will corrode synchros. If they are listed as yellow metal compatible they will be fine.

I don't have a manual though, so anything I know about them is info absorbed via osmosis, and can be anything from correct to a beautiful work of fiction.

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Kastein has it right--and I have yet to see any "GL-3/4/5" gear lube marked as safe for yellow metals.

Motor oil and gear lubes have different methods of calculating viscosity, so a gear oil viscosity does not compare to a motor oil viscosity.

So it doesn't really matter if its dex III or ATF in the TC? on my 98 I ran dex and on my 01 I ran atf+4. Debating on which to put in my 99?

I doubt it'll matter at all - the transfer case (at least in a 231, a 242 may be different) has no clutches/friction materials, just gears, so it really is not picky as long as it's approximately the right viscosity and has some detergents in it. I usually use dex III as I keep a cheap 5qt container of that around for the transfer case and making penetrating lube.