Looking for 4t65e advice

[easymachtdas]

Hello,

after spending hours researching, I decided to make a new post asking about Dexron 3 vs dexron 6.

I just did a drain and fill on a 2007 Uplander that has a 4T65e (M15) transmission. I ended up using Supertech high mileage dexron 3 fluid. I understand dexron 6 is recommended for this year model, and am curious how detrimental the mismatch of fluid is. As I understand after reading through the internet, dex 6 is a lower viscosity fluid, which matters a lot more for newer gm autotrans with 6 gears.

Any input is welcome. I guess my main question is whether or not i need to drain this dex 3 asap and replace it with dex 6. Considering its an older transmission I am hoping there is no harm using dex 3.

 

[Lubener]

Dex 6 is the replacement to Dex 3 and is backward compatible with transmissions that originally spec'd Dex 3. I don't believe there is a detriment using Dex 3 in your 4T65E as I believe that is what your transmission originally came with. The Dex 6 is more shear stable as miles are accrued on the fluid than Dex 3, so Dex 3 won't last as long as Dex 6. Some people use Maxlife with good results but I have no experience with it. My personal experience with Dex 6, I noticed harsher shifts with my 4T65E transmission when hot ( Probably due to the lower viscosity ) after switching to DEX 6.

 

[slacktide_bitog]

You do not need to drain it asap, but Dexron VI is better. Just replace it when convenient.

Also, if your transmission doesn't have a drain plug, get an aftermarket pan that has one. It will make future ATF changes much easier

 

[Trav]

Other than a hardened 4th gear input shaft and a few minor modifications the 4T65E is the same old unit that spec'd dex III, in these and other dex III transmissions I use a TES-295 fluid (I use Mobil Delvac 1 ATF), it stays in grade and provides really nice shifts. Not cheap but due to its stability has a longer change interval. Amsoil ATF (not the fuel efficient ATL) works very well and also has a long life.

https://www.mobil.com/en/lubricants/for-businesses/heavy-duty-lubricants/products/mobil-delvac-1-atf