Thread: High mileage transmission, change fluid or not?

I had over 200k miles on my transmission when I sold the car. I had no cooler on it, other than the factory radiator cooler. I changed the fluid once, and had lots of deep 12 second passes, and a few in the 11's. Yet, I experienced no internal failures. So you can't make a generalized statement like you did and assume it's correct for everything. It most likely has more to do with your specific circumstances than anything.

AGAIN! I am not saying that you cannot go 200K miles on a 4T65E unless you have a cooler!

Having double stack coolers outside of the radiator which I have been doing for 40 years now and on many transmissions for 100's of thousands of miles on many different cars will NOT harm the tranny as previously stated by the uninformed. THAT statement is correct! Period.

And NO my experience with the GP is NOT necessarily my particular circumstance since I have said now multiple times ^^^^that the big cooler setup outside of the factory radiator cooling has been wildly successful with MANY cars of mine over many years/miles with zero tranny failures. You know how many 4T65E tranny failures that I personally know with miles less than 100K miles? Too many to list.

When you have personal experience with many examples like I do with the cooling method described over 40 years on easily 10+ transmissions of different types, please let me know. Otherwise, respectively disagree and call it a day while you are ahead,

I do have quite a bit of experience with lots of other vehicles besides 4t65e's. They only one I've ever had problems with was the one with an aftermarket external cooler. All the other factory setups had no problems well over 200k.

Clearly none of those was a 4T60E. If you claim they were, you're delusional.

2001 GP GT owner. I changed the fluid and filter two weeks ago. The fluid was brown but not burnt. Someone changed it in the past because it was an aftermarket gasket. I put a bottle of Lucas and a little over six quarts of DexVI. This thing shifts perfectly, no shudder or slamming shifts. OD kicks in at 45mph which is lower than the 50 mph I was used to with my 2006 and 2008. No neutral drops like both of my GXP's did. Amazing longevity for a transmission.

Last call for this thread over many years now!

The 01 GP with said coolers, accumulator springs, religious tranny filter and fluid changes, finally was put to rest in July 2023 at 236,000 miles on the odometer due to frame rust. I drove it to the junkyard with the 4t65E still shifting perfectly like the day it was new. OEM 3.1 V6 also was perfect, never burning an oz of oil between 5K oil changes. Really was a shame that the body and frame gave up with the tranny and engine still perfect!

GP was a great car over all 236,000 miles I owned her, from new from the dealer.