Thread: Opinions on Dex 6...

Im on the stock 4t65e, just a couple hundred over 50k and Im gunna drain and replace my fluid and filter... checked the fluid yesterday and it's just a little bit darker and doesnt smell burnt, good level, seems in good shape.

Question is, I've heard some people say bad things about the dex 6.. slipping and weird shifts and other stuff..

I've also read that it's only a problem with older transmissions with more wear and tear, or transmissions that havnt been taken care of.

What are your opinions, think I'll be ok with it since my tranny is relatively young and in good shape? Think it'll be a bad move?
Anybody have good experiences with it?

From what ive read the older your car is the more likely you want to stick to dex3. I have an 01 and just did my shift kit and replaced with dex3 no probs at all, id say do that to avoid probs. But if your car is newer then I dont see why not.

I know of many guys even 4T60's using Dex 6 and reporting better shifts and cooler temps. Seems good. Walmart has a good priced in house brand of it that most are using and like.

Replaced Fluid and Filter about 8k ago on my 99 GTP 4t65hd and used GM Dex6. Shifts seem a little more solid than before, but the tech said it was pretty dark and a little burned. I doubt if the previous owner ever did a change and i had it done at 80k miles, but its holding strong, cant say anything on temps tho

yes dex 6 is perfect for 04+ grand prix's but in the 97-03 grand prix's dex 6 is thinner than dex 3 and that causes them to slip and not shift perfect in WOT. so i recommend to get dex 3 in a 97-03 and dex 6 in 04+

I have replaced Dex 3 with Dex 6 in both my '04 Trailblazer and '01 GPGT. If you read what GM states about Dex 6, they say it is completely backwards compatible.

In both cases, the transmissions operated smoothly and flawlessly after the switch.

On the GP, I installed a Transgo shift kit as well to eliminate the Max-Adapt shift problem that plagues the 4T65e......no more hard shift and nice, smooth performance.

Idk my tranny seems to like the Dex 6 more than the Dex 3, when I first got this car in February of last year, I dropped the pan and changed the filter fluid and put in Dex 3 and it turned black after 3 or 4 months so I dropped the pan again changed the filter again and added Dex 6 instead the fluid is still nice and red and the car shifts a lot better than it did with the Dex 3.

Originally Posted by That Canadian Guy

Look for a synthetic dex III.

Amsoil ATF is a good synthetic D3 to use.

Originally Posted by mechguy

Noteworthy is that Dex 6 viscosity is allegedly much more stable with number of test cycles, compared to Dex 3. Viscosity of Dex 3 will be higher than Dex 6 initially, but not after many heat cycles.

Probably have slightly lower trans temps with Dex 6.

X2 I just had my fluid changed to D6..my trans. temp gauge barely moves.

Is there a point where you should not change the tranny fluid because it causes slips and can hurt the tranny? I thought I read that somewhere. Just wondering because I have around 93k miles and I don't know if its ever been done. Should I change or no?

"GM states about Dex 6, they say it is completely backwards compatible."
Enough said......

Should I change or no?[/QUOTE]


It would be good to drop the pan, change the filter with a GM/SPX original USA made filter, and use synthetic D3 or D6 fluid. I used valvoline synthetic D6 and am happy with the outcome.