When not to change AT Fluid

[SnyderXJ98]

Thinking about doing a transmission service to my XJ on Thursday. My XJ has 206,000 miles on it and I dont know the last time a transmission service was done on it. Ive heard that a service after a long time can cause the transmission to fail. When i checked the fluid last it was in between red and brown and didnt smell burnt. What do you guys think?

[XJ Wheeler]

If its operating fine you should be okay. But if you want to okay it safe you can do a 50/50 fluid change. That's where you use 50% new fluid and reuse 50% of the fluid that you drain.

[4.3LXJ]

If you drain the pan, you only get rid of 2.5 quarts anyway. The rest is in the torque converter. So unless you drain that, don't worry about it

[ArmyGuy45]

If you drain the pan, you only get rid of 2.5 quarts anyway. The rest is in the torque converter. So unless you drain that, don't worry about it

Does this mix to give you the 50/50 fluid change that people are talking about? Does it all mix?

[4.3LXJ]

Yes it all mixes

[ArmyGuy45]

Yes it all mixes

Do you need to engage the 4wd in order to get it all to mix?

[4.3LXJ]

No, just drive it

[NW99XJ]

you'll also want to (with the engine running the parking brake on & the brake pedal depressed) cycle thru ALL the gear positions (P , R, N, D, 3, 2, 1) ....stopping for a good moment (maybe 30-60 seconds) in each position.

This allows all the valves and solenoids to open and circulate all the fluids together.

[ArmyGuy45]

you'll also want to (with the engine running the parking brake on & the brake pedal depressed) cycle thru ALL the gear positions (P , R, N, D, 3, 2, 1) ....stopping for a good moment (maybe 30-60 seconds) in each position.

This allows all the valves and solenoids to open and circulate all the fluids together.

Will do thx for the tip!

[nickyg]

If its operating fine you should be okay. But if you want to okay it safe you can do a 50/50 fluid change. That's where you use 50% new fluid and reuse 50% of the fluid that you drain.

I've heard this before, but can anyone explain why you would want to do a 50/50 change or not at all?
Don't get me wrong, I don't doubt you guys expertise and belive what you say. Just looking to feed my brain worm.

[bluedragon436]

I'll def be doing this with my XJ when I do the filter and fluid change out... Can't wait to have that peace knowing that it has been taken care of...

[89Laredo]

I drain the pan and refill every spring.
Make sure you use Dexron III.

[bulrid8]

I've heard this before, but can anyone explain why you would want to do a 50/50 change or not at all?
Don't get me wrong, I don't doubt you guys expertise and belive what you say. Just looking to feed my brain worm.

Older trans that haven't been serviced much, lose the friction material off the clutches. But that material is still floating in the fluid, so it helps it grab ok. When you change all the fluid at once, you can all the sudden have problems, due to the clutches slipping. That is where the myth came from of not changing fluid in old trans.

If you do a 50/50 change, you still leave some material in the old fluid. So it helps it keep going stronge. If trans has been serviced often. Change all you want. Won't harm it.

Sent from my ADR6400L using Tapatalk 2

[4.3LXJ]

All I have to say is we took an AW4 with 357K that was slipping and did two oil changes and got rid of the black oil and replaced it with pink oil. Pretty clean now and working perfectly. Nuff Said

[Brasscatz]

All I have to say is we took an AW4 with 357K that was slipping and did two oil changes and got rid of the black oil and replaced it with pink oil. Pretty clean now and working perfectly. Nuff Said

I suppose that since it was already slipping, there was nothing to lose by replacing the fluid :P ;)

[AnarchyBurger]

Thinking about doing a transmission service to my XJ on Thursday. My XJ has 206,000 miles on it and I dont know the last time a transmission service was done on it. Ive heard that a service after a long time can cause the transmission to fail. When i checked the fluid last it was in between red and brown and didnt smell burnt. What do you guys think?

Using a transmission flush machine can mess up an old transmission, replacing the fluid manually can only help. You should probably drop the tranny pan and replace the filter. You can usually get the filter and a new seal in a kit. Then get a hand held fluid pump from Harbor Freight or Walmart. Stick the sucky end the of pump tube down in the transmission fill tube and suck out as much fluid as you can. Add in fresh transmission fluid.

[Mudderoy]

I've heard this before, but can anyone explain why you would want to do a 50/50 change or not at all?
Don't get me wrong, I don't doubt you guys expertise and belive what you say. Just looking to feed my brain worm.

My mechanic told me he has seen vehicles have their transmission fluid changed and then won't go into gear afterwards.

The bands are so worn that only the band coating, debris in the transmission fluid, is what is allowing them to grab. 50/50 in the hopes that enough of that material suspended in the fluid will be sufficient to allow the transmission to engage and not slip.