Replace transmission fluid or no?

[nagrom46]

I’ve got a new to me 2012 that has an excellent service history but no known history of a transmission flush or drain and fill.

Currently sitting at 150k miles and transmission seems to be operating perfectly fine.

Is it worth the risk to even mess with the fluid at this point?

 

[r2m]

I’ve got a new to me 2012 that has an excellent service history but no known history of a transmission flush or drain and fill.

Currently sitting at 150k miles and transmission seems to be operating perfectly fine.

Is it worth the risk to even mess with the fluid at this point?

YES!
With all due respect, there's been quite a bit of discussion on this. Have you searched?
Yeah, I think the manual says you don't ever need to, but most of us have (I personally have), especially if you're hauling a trailer, huge tires or a lot of weight.

 

[ericm979]

There's a theory that a high mileage transmission with worn clutches may be working ok because the old fluid in it has a lot of crap in it which increases friction. Replacing the fluid gets rid of the crap and then the clutches slip. I think there's at least one person here who had a trans fail after a high mileage oil change.

I think I'd try to pull some fluid out of the trans with a syringe and hose in the fill hole, and examine it. If it's not too dirty then its safe to replace the fluid. Maybe an oil analysis would be useful to know what too dirty is.

I suspect that if the only thing making the trans work is dirty fluid, it's days are already numbered, especially with modern transmissions with a ton of solenoids and valves. But that might be 10k more miles.

 

[nagrom46]

There's a theory that a high mileage transmission with worn clutches may be working ok because the old fluid in it has a lot of crap in it which increases friction. Replacing the fluid gets rid of the crap and then the clutches slip. I think there's at least one person here who had a trans fail after a high mileage oil change.

I think I'd try to pull some fluid out of the trans with a syringe and hose in the fill hole, and examine it. If it's not too dirty then its safe to replace the fluid. Maybe an oil analysis would be useful to know what too dirty is.

I suspect that if the only thing making the trans work is dirty fluid, it's days are already numbered, especially with modern transmissions with a ton of solenoids and valves. But that might be 10k more miles.

You nailed my concerns perfectly.

Thanks for that suggestion. Think I will do that first and go from there.

 

[Rednexus]

In my opinion, judging that the fluid is so full of clutch material that it may cause a transmission failure is always going to be subjective. The fluid in my A750F was pretty dark when I changed it, but it's been perfect since the change (nearly 30K miles). With a Blackstone oil analysis, it might tell you the fluid is fine, or that it is cooked, but it won't be able to tell you if it is cooked and that changing it will cause the transmission to fail. And, if you were to keep driving on the cooked fluid as indicated by Blackstone and/or a visual inspection, wear would definitely be accelerated relative to fresh fluid. If the transmission was otherwise fine, this could lead to a replacement much sooner than if the fluid had been changed.

My recommendation is to just change the fluid. If the trans were to be so far gone that the fluid change would push it to failure, at least it would fail now and not at some undetermined time in the future when you are enjoying your GX in the middle of nowhere. When you do change the fluid, it's worthwhile to drop the pan, clean out the magnets and any gunk, replace the filter, and do a full fluid exchange where all ~16 quarts are replaced.

 

[nagrom46]

In my opinion, judging that the fluid is so full of clutch material that it may cause a transmission failure is always going to be subjective. The fluid in my A750F was pretty dark when I changed it, but it's been perfect since the change (nearly 30K miles). With a Blackstone oil analysis, it might tell you the fluid is fine, or that it is cooked, but it won't be able to tell you if it is cooked and that changing it will cause the transmission to fail. And, if you were to keep driving on the cooked fluid as indicated by Blackstone and/or a visual inspection, wear would definitely be accelerated relative to fresh fluid. If the transmission was otherwise fine, this could lead to a replacement much sooner than if the fluid had been changed.

My recommendation is to just change the fluid. If the trans were to be so far gone that the fluid change would push it to failure, at least it would fail now and not at some undetermined time in the future when you are enjoying your GX in the middle of nowhere. When you do change the fluid, it's worthwhile to drop the pan, clean out the magnets and any gunk, replace the filter, and do a full fluid exchange where all ~16 quarts are replaced.

Great advice.

This is more what I was thinking prior to making this thread. Thank you

 

[ABCruiser]

Not that it would be a direct comparison but I was having issues with my 2009 scion tc. The car would shudder when I was stopped. I changed the transmission fluid and now it runs super smooth. The car had 230,000 miles on it when I changed it and most of those were in city driving. I doubt the previous owner ever changed or checked the trans fluid. I’ve also heard that the issue with changing fluid in higher mileage vehicles would be problematic for older vehicles.

 

[BigSwede]

I would do a simple drain and fill. That will change out 3-4 quarts and gently introduce new fluid, avoiding a shock to the system. Repeat later as necessary.