What is the best fluid to run in an original TH400? (No synthetic please / No Type F please) -

[Matt Frediani]

I need to change the fluid , install a pan with a drain p lug/ filter and seal up leaks on my OEM V2500. It has a TH400 and I want to find the right oil to use.
I want to stay away from synthetic to avoid leaks. can you please help me with a brand name and where I can order it?

Thx
Matt

 

[75gmck25]

Dexron III is recommended for the older GM transmissions.
Dexron VI will work in a pinch, but may affect stall speed and other functions.

 

[Matt69olds]

“Synthetic fluids cause leaks!!” is another myth that just won’t die.

If the trans isn’t leaking now, synthetic won’t cause it to leak.

Valvoline synthetic is about 25 bucks a gallon at AutoZone. Supposedly it’s even cheaper at Walmart, but I have never seen it at my local store. For 25 bucks a gallon it’s pretty hard to beat that price

 

[nvrenuf]

Why not Type F ? I ran it I’m my old truck and never had an issue. I was told it has better anti foaming additives and a higher boiling point.

 

[idahovette]

Almost all the brands I see out there are DexIII/Mercon mixtures???

 

[DoubleDingo]

I can't get Dexron III here, so I switched to Dexron/Mercon V.

 

[Bextreme04]

I'm running the Valvoline Dex/Merc in my 1980 K25 with a TH400. Works great. I run the Valvoline MaxLife(which is the synthetic Dex VI version) in my 2011 K1500 Suburban and have never had an issue either. The Standard Dex/Merc is a non-synthetic Dextron III replacement while the MaxLife is Synthetic. I ran the MaxLife for a while after I first got the truck and had no leaks or issues either, but it isn't necessary.

The Standard Valvoline Dex/Merc is only $13.97/Gal at my local Walmart
https://www.walmart.com/ip/Valvolin...viuqhYLWNe0d7KVU_4xoCtEcQAvD_BwE&gclsrc=aw.ds

Maxlife is ~$17/Gal there too. They generally have them both in stock, as well as oil and coolant for significantly cheaper than the local auto parts store.

 

[73c20jim]

Since you are only dropping the pan the amount of ATF you add is a small percentage of the total amount in the transmission, I don't think it will make much difference what you add..

 

[Vbb199]

Dex iii

 

[Turbo4whl]

Dexron VI is the replacement for Dexron III.

My question for everyone, how can Dex/Merc replace 3 different Dexrons and 4 Mercons?

The answer is it cannot! Different friction modifiers and viscosities, just to name a couple.

@Matt Frediani , use Dexron VI.

 

[78C10BigTen]

Idk if its dex or mex or both but this is what i use in all my vehicles.

 

[AuroraGirl]

Dexron VI is the replacement for Dexron III.

My question for everyone, how can Dex/Merc replace 3 different Dexrons and 4 Mercons?

The answer is it cannot! Different friction modifiers and viscosities, just to name a couple.

@Matt Frediani , use Dexron VI.

Ask GM and they will tell you it works great for all applications of Dexron, Dexron II, Dexron III and 2006+ needs Dex VI. But they also dont want you to ask how and the tsb for it has some cover-ass-wording sorta

You must be registered for see images attach

You must be registered for see images attach