Best Transmission Fluid?

[6OhDenali]

Im sorry if this has been asked, i tried searching and found lots of different information but not a direct answer...
I have an 05 Denali, 125k and doing a tranny filter, fluid and adding a 2nd cooler. No problems yet but im trying to increase longevity. I just got the truck 2 months ago and im going through it all so i know its done right. Fluid is light pink, no metal in it that i could see.

What is the best fluid to use? The manual says Dex III, but ive seen theres Dex 5 and 6 now. Are those better? Or is my tranny not made for those?

Thanks guys!

 

[rockola1971]

You are starting with the first step of longevity of a tranny. Transmission coolers take care of the #1 killer of a tranny. HEAT! I stick DEX 3 in mine. I dont like to try to reinvent the wheel.

 

[6OhDenali]

Ordered a new 10x15.5" cooler off amazon. Going to run it along with the stock tiny one. I didnt see any reason why i shouldnt run both together.
And i like the way you put that about the Dex3. I know it certainly won't harm the tranny by running what it was designed to run.

 

[inmypassatlife]

The problem with dex3 fluids is that after 2006 there were no more certifications of it and is no longer policed by GM...meaning manufacturers don't have to stick to a certain code when making it any more

 

[01ssreda4]

I use the Dex/Merc. No issues.

 

[6OhDenali]

So if dex 3 isnt regulated anymore, whats the best way to ensure im getting the best fluid? I always have stuck with OEM fluids, toyota, honda etc (unless it was my old square body GMs). This is my family vehicle now so i want the best for it. Are Dex 5 and 6 regulated?