When should I change the transmission and transfer case fluids?

MikekiM

MikekiM

TJ Addict
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Nov 3, 2018
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East of Montauk, NY
Just past my one year anniversary with my 2000 TJ. Three owner vehicle with me being third. I purchased it with 59,000 miles and was told the first owner (who put all the miles on it according to Carfax) was a master mechanic at a local dealership. I’ve convinced myself it was taken care of, and it seems to have been, with the only issues being sitting too long in the second owners garage.

None the less, I have done a ton of preventative maintenance since it is my DD. I have yet to change the lube in either of the NV3550 or NV231. Every thing works fine with only a chattering input shaft bearing that needs attention.

I’ve put about 12k road miles on it. Should I do any maintenance on the transmission or transfer case?
 
If the fluids have not been changed, I would go ahead and do it. You at about 75k miles wouldn’t hurt. You are looking at about 4 qts of fluid and about 1/2 hour under the Jeep.
 
I tend to follow factory service intervals fairly closely. I don't know what those are specifically on these Jeeps, but I have an '05 Dodge truck that suggest trans/transfer case/diffs are to be changed every 30K. I change them every 25K because it's easier to spot/remember on the odometer. Figuring that MoPar would have a similar schedule across the board, I'm doing the same with my jeep.
 
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It’s easy to do. I’d put redline mtl in the transmission. It definitely improved the feel of my nv3550. The t case takes gear oil I think? May wanna check that one to confirm. It’s a pretty easy task, get a big drain pan.
 
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TRE3TOP said:
It’s easy to do. I’d put redline mtl in the transmission. It definitely improved the feel of my nv3550. The t case takes gear oil I think? May wanna check that one to confirm. It’s a pretty easy task, get a big drain pan.
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Redline MTL is the right stuff for an NV3550 or NSG370. The transfer case takes ATF, any good quality type of ATF is fine... it's not fussy about what type of ATF it gets like an automatic transmission is.
 
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I just had my Jeep transmission rebuilt. The guy has built hundreds of transmissions. He swears up and down to not change the transmission fluid.

I had my Duramax in for maintenance and asked the mechanic about it. He said now all they do is change the external filter and top it off.
 
HDRider said:
I just had my Jeep transmission rebuilt. The guy has built hundreds of transmissions. He swears up and down to not change the transmission fluid.
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So the guy whose livelihood is rebuilding spent transmissions suggest not changing transmission fluid and filters. :unsure: I see nothing suspicious. ;)

HDRider said:
I had my Duramax in for maintenance and asked the mechanic about it. He said now all they do is change the external filter and top it off.
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This is pretty much the route I go and suggest to others. Drop the pan to change the filter(s) and refill. That usually cycles out about 1/3 of the fluid each time. Doing so on a factory service schedule, I've had 3 vehicles go 250K+ with original transmissions.
 
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HDRider said:
I just had my Jeep transmission rebuilt. The guy has built hundreds of transmissions. He swears up and down to not change the transmission fluid.
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He's just repeating an old wive's tale or trying to keep his automatic transmission repair business going. When automatic transmissions go bad after an ATF change it's because they were ready to fail anyway. Keep in mind few people resort to flushing an automatic transmission with fresh ATF unless the transmission is already having problems and ready to die anyway. That's how rumors get started.
 
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Red Line (50204) SAE 75W80 API GL-4 Manual Transmission and Transaxle Lubricant - Car Gear Oil - 1 Quart Bottle https://a.co/d/48aO9MS

You can probably get it in 2 days to your door. You’ll need two. You’ll also want one of these.

Capri Tools 3-0545 17 mm Hex Bit Socket, 1/2-Inch Drive, Metric https://a.co/d/aWQJzDQ
 
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Jerry Bransford said:
He's just repeating an old wive's tale or trying to keep his automatic transmission repair business going. When automatic transmissions go bad after an ATF change it's because they were ready to fail anyway. Keep in mind few people resort to flushing an automatic transmission with fresh ATF unless the transmission is already having problems and ready to die anyway. That's how rumors get started.
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I don't know enough to argue about it one way or the other. I will try to share his position. Most everyone here is going to know the mechanics of a transmission better than me.

He says the friction material on the bands wears off and becomes suspended in the ATF. If the material is off the bands and no longer in the fluid then the trans will not function as it should.

Apart from the trans mechanic, a high school friend of mine worked rebuilding transmissions since he was a kid, and retired doing it, recommended adding friction modifier to ATF.

I admit, not changing the ATF goes against everything I have been told.
 
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Jerry Bransford said:
He's just repeating an old wive's tale or trying to keep his automatic transmission repair business going. When automatic transmissions go bad after an ATF change it's because they were ready to fail anyway. Keep in mind few people resort to flushing an automatic transmission with fresh ATF unless the transmission is already having problems and ready to die anyway. That's how rumors get started.
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I heard something similar.

Dont flush an old auto transmission because it relies on the dirt deposits and build up to maintain pressure required to shift.
 
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My neighbor never changed the transmission fluid in her Jeep (318,000 miles) and she never washed the engine. She told me all the dirt keeps the seals from leaking. :unsure:
 
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cherrybomb said:
it's amazing how half the people in this thread are talking manual transmission and others auto
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True. And to clear up one thing that might have been said just out of habit, our Wranglers don't have transaxles like my old 1966 VW beetle did. I.E. a transaxle has the transmission and axle combined together which isn't the case with any of our Wranglers. :)
 
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