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How to change manual transmission fluid?

126K views 89 replies 32 participants last post by  wtroger 
#1 ·
I would like to change the fluid in my 1997 Wrangler's transmission. It is a 5 speed manual. I'm asking about it because this is something I haven't ever done before. As I understand it, you just remove a drain plug, drain the old fluid, and replace the plug. Then there's another plug up higher, so you take that plug out and then add the new fluid until it gets level with this plug. Sound correct?

I also wondered if anyone knows of anything unexpected a person can run into doing this, and if anyone knows what the best fluid to put back in the tranny would be. Most of the Jeep's miles are driven on-road, but it does get the occasional trip off-road when time permits. My local auto parts store is Advance Auto.

Thanks!
 
#2 ·
I can't recall without looking but I believe you can find that info in one of those stickys up top of the screen. If not, it's pretty straightforward. My only issue I want to say was the crowded area makes getting the new fluid back in tough without a pump of some sort.
 
#3 ·
first make sure you can get the fill plug out first (drivers side about mid way up), the last thing that you want to happen is to drain the fluid and then not be able to get the fill plug out because of it being too tight or stripped.

having a "bottle fluid pump" is handy to get the new fluid in.

i think for your year, most here have switched to 10/30 motor oil. others can correct me if this is not correct.
 
#13 ·
You're right on the money on all counts. I've got a '97 with a manual and I switched to 10/30 last year. The tranny shifts way better than it ever has and i no longer have problems shifting into 2nd gear on cold mornings.
 
#4 ·
Remove fill plug, then remove drain plug. The rain plug has a magnet in it so make sure you clean the metal shavings off. You can even drain it with the skid plate on, I use cardboard to deflect the oil.

Put drain plug back on. There are two ways of doing this:

1. Remove the shifter from the transmission and poor the oil in there until it comes out the fill hole.

2. Get a handheld pump and pump the oil into the transmission through the fill hole until it runs out.

I personally like option 1.

^^^Yes, 10w-30 motor oil is the "new" spec. It's what I put in there and am really happy with it. Really smoothed out the shifting.
 
#6 ·
redline mt-90 or royal purple synchromax (ive got RP in mine now and will switch to redline). i have not heard of anyone using 10w-30 wt oil and would not use it in your manual transmission. in fact without doing any research into it i would say that it could damage your synchronizers because the oil meets nowhere near the viscosity requirements or has the right properties (waiting to hear the correct answer from jerry now). and if i remember correctly the fill plug sits decently high up, if you were to fill all the way to that, you would have way too much fluid, im pretty sure its 4 qts. better by yourself a manual to see what the factory specs are for amount of fluid and what specs the fluid needs to meet. only about 15 bucks from your local parts store. well worth the investment.

oh and if you get a fill tube long enough, the bottle will fit up in front of the fire wall allowing the oil to drain in the tranny. either that or a pump will work.

edit: in just reading the link real quick from stuoffroad, about 3.25 qrts.
 
#7 ·
redline mt-90 or royal purple synchromax (ive got RP in mine now and will switch to redline). i have not heard of anyone using 10w-30 wt oil and would not use it in your manual transmission. in fact without doing any research into it i would say that it could damage your synchronizers because the oil meets nowhere near the viscosity requirements or has the right properties (waiting to hear the correct answer from jerry now). and if i remember correctly the fill plug sits decently high up, if you were to fill all the way to that, you would have way too much fluid, im pretty sure its 4 qts. better by yourself a manual to see what the factory specs are for amount of fluid and what specs the fluid needs to meet. only about 15 bucks from your local parts store. well worth the investment.

oh and if you get a fill tube long enough, the bottle will fit up in front of the fire wall allowing the oil to drain in the tranny. either that or a pump will work.

edit: in just reading the link real quick from stuoffroad, about 3.25 qrts.
I use 10w-30 and it works great. Its the new oil your supposed to use in the AX-15.

First remove the FILL plug.
Then the drain
put the drain back in
Fill it up with 10w-30 using one of those crappy pumps from autozone
Fill plug back in
Your good to go

IIRC the fill/drain polugs are 15/16".
 
#11 ·
I visited Advance Auto this afternoon. They recommended gear oil...I don't remember what weight. They said 3.4 quarts were required. Hopefully tomorrow I will to change the fluid.
 
#18 ·
I believe Advance suggested 75w-90 gear oil.

I did the change today. The old oil was ugly! It looked like it was actually dirty......as in real DIRT. I have not had the Jeep long, but I bet all 164k miles were on that old oil. I ended up using a long piece of hose to get the oil container beside the vehicle and above tranny level. Advance said it requires 3.4 quarts, and I would say it took around that much, then started to come back out the fill hole, so I considered it full.
 
#20 ·
Please tell us that you didn't put 75w90 in your transmission. A good quality 10w30 motor oil would have been best. The 75w90 (SO LONG AS IT IS NOT GL-5) will not hurt anything but will make your trans shift like crap when cold. NO GL-5! it will wreck the bronze syncros. Ask me how I know? If you put in a gl-5 rated gear oil and it doesn't say that is is specfiicly for soft metals like bronze. I highly recommend that you change it before you drive it.
 
#25 ·
the weight you selected is ok, but, as stated above. most gl-5 classification lube contains additives that attack yellow metals like brass and bronze. our manuals fall into this group.

gear lubes that meet the gl3 and gl4 classification are safe to use but are difficult to find. this is why most here have converted to 10/30 motor oil.

there are other choices also, some gl-5 are safe, i think amsoil and royal purple make this claim, and red line has a product. but again 10/30 motor oil (dino or synthetic) is a very easy choice.

do drain and refill.
 
#26 ·
I emailed Warren Oil Company, who distributes the Coastal gear oil I just put in my tranny.

I asked:
I drive a 1997 Jeep Wrangler. It is a 4.0 6 cyl, 5 speed, which I believe means it has an AX-15 transmission. I recently changed the transmission oil, and replaced it with "Coastal SAE 75w-90 gear oil, API service GL-5". Since then, I have been reading how GL-5 oil is bad for the AX-15 transmission, because the sulfer in it can harm the bronze parts. Do you have any information about this?

They said:
According to my Check-Chart Lubrication Guide your vehicle would require a 75W-90 GL-5 Gear Oil for your AX-15 manual transmission. So you do have the correct fluid. The additive packages for GL-5 gear oils have changed a lot over the years. Many years ago your concern about GL-5 packages and “yellow metals” was correct. Warren Oil Company uses a GL-5 additive technology that will not harm “yellow metals”, such as brass or bronze.

Sincerely,

Gary Whiteside

Corporate Vice President

Quality & Technology

Warren Oil Company, Inc.


So perhaps the GL-5 technology has been improved and is no longer harmful. Does anyone have FIRST HAND experience / information about using GL-5 oil, and knowing that the oil harmed their tranny? I just wonder how much is rumor and how much is first hand info and confirmed.

Thanks all
 
#27 ·
I emailed Warren Oil Company, who distributes the Coastal gear oil I just put in my tranny.

I asked:
I drive a 1997 Jeep Wrangler. It is a 4.0 6 cyl, 5 speed, which I believe means it has an AX-15 transmission. I recently changed the transmission oil, and replaced it with "Coastal SAE 75w-90 gear oil, API service GL-5". Since then, I have been reading how GL-5 oil is bad for the AX-15 transmission, because the sulfer in it can harm the bronze parts. Do you have any information about this?

They said:
According to my Check-Chart Lubrication Guide your vehicle would require a 75W-90 GL-5 Gear Oil for your AX-15 manual transmission. So you do have the correct fluid. The additive packages for GL-5 gear oils have changed a lot over the years. Many years ago your concern about GL-5 packages and "yellow metals" was correct. Warren Oil Company uses a GL-5 additive technology that will not harm "yellow metals", such as brass or bronze.

Sincerely,

Gary Whiteside

Corporate Vice President

Quality & Technology

Warren Oil Company, Inc.

So perhaps the GL-5 technology has been improved and is no longer harmful. Does anyone have FIRST HAND experience / information about using GL-5 oil, and knowing that the oil harmed their tranny? I just wonder how much is rumor and how much is first hand info and confirmed.

Thanks all
I wouldn't trust them. How can they say they have a additive package that is safe for soft metals, when the description of the gear oil clearly states it has sulfer/phosphorus in it! Just drain the oil and put 10w-30 motor oil in it. Unlike this guy at as some oil company, Chrysler has actually spent money in R&D and are saying 10w-30 motor oil is the new spec.

Plus if this guy is going by what the manual says, the some early model manuals were printed wrong and Chrysler later sent out an addendum for the manual.
 
#28 ·
Go buy a gallon of MT-90 from summit or jegs, cheaper that way. Its around 50 bucks or so iirc. Loosen the fill plug first to be sure it can be taken out. Pull the drain plug and let it drain. Clean off the magnets and reinstall the drain plug then using the fill plug using a bottle pump. Be sure to get at least 2 because I was overzealous and broke one then had to rig up some tubing and a funnel to fill it back up such a pain. Just till ur finger can touch the fluid is the right amount.
 
#29 ·
josh_br, it sounds like you did the proper research and found some valuable info. i agree with the reps assessment that times have changed and improvements have been made. i would print out his response for future reference.

freeskier93, i doubt that the VP of a company would have much to gain by "lying" to one customer over the cost of a few quarts of oil. also, product tech improves everyday, and by warren changing their additive package to be more compatible is very much in line with what companies do everyday. the approval of 10/30 was revised as a convenience, rather than improved reliability. do you really think the chrysler cares about the reliability of a 13 year old tranny.

we have known for some time that some gl-5's are "yellow metal safe", we just found out that at least one more is.

i say good job josh_br.
 
#30 ·
Yes I'm sure Chrysler made 10w-30 the new spec because of price, but that still doesn't change the fact that it's a proven safe oil to use.

OP I would email the guy back and ask what PPMs of sulfer/phosphorus are in the oil. But seriously, rather be safe than sorry and just put different oil in it. Either the guy is lying or they need to change the description of their oil.

Again, this quoted straight from Advance Auto:

Multipurpose sulfur/phosphorous type gear lubricants designed for API Service Classification GL-5. Limited Slip applications for top-off only. Recommended for use in passenger cars, light-duty trucks and sport utility vehicles.
Straight from their website: http://www.warrenunilube.com/gearoils.html

Coastal GL-5 Gear Oils are multi-purpose sulfur/phosphorous type gear lubricants designed for API Service Classification �GL-5. Coastal GL-5 Gear Oils are compounded with highly refined base stocks and additives to ensure extreme pressure characteristics, antiwear, corrosion inhibition, rust preventions, low pour point, and antifoaming tendencies. Limited Slip applications for top-off only. Coastal GL-5 Gear Oils are recommended for use in passenger cars, light duty trucks and sport utility vehicles. Always check owner�s manual for proper recommendation.
 
#36 ·
While I agree that times have changed. Who knows how informed the V.P. actually is about sulfer leveld in his product. It was only a few years ago 2005 that my buddy and I changed his trans because of a sulfer GL-5 gear oil. The used car dealer did him a favor by changing the trans, tcase, and diff fluids before he bought it. Shiffted fine off the lot then at about 1000 miles it started showing signs of syncro problems. Not worth the risk IMO.
 
#38 ·
I don't know if you will ever get an agreement on the "best" fluid to use, but you basically have 4 choices that fall with into 2 categories. From my understanding these are the only fluids that meet spec, many other people have used other stuff.

Synthetic - Royal Purple Syncromax or Amsoil Synchromesh

Non-synthetic - Pennzoil Synchromesh, or Mopar fluid from the dealer

2 qts should do fine.
 
#43 ·
Earlier I posted about 10/30 in the ax-15, I would like to update to say I am very unhappy with it. At first it was nice because I had come from such old oil, but after a while the shifting became hard and "notchy". I will be switching to Redline MTL next engine oil change intervel.
 
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