which ATF am I supposed to use?

2005 Suburban K1500LT: I am going to do a complete ATF exchange via some flush/filter/gasket method asap. I thought I was supposed to use the Dex VI fluid, but more reading tells me it came with the Dex III. While I might still go for the Dex VI I don't think I need the most expensive brands if it was already set up for the Dex III. I've read dozens of threads and posts about the old "this is better than that" opinions. PB wants to use Pennzoil, but I'd rather have Castrol if I do that through them. I'd just as soon use Supertech (approved by GM) for 1/2 the price if I have my son do it.

I just want to make sure I get ALL the old stuff out and put good stuff in. PLEASE: no amsoil ads!

2005 Suburban K1500LT: I am going to do a complete ATF exchange via some flush/filter/gasket method asap. I thought I was supposed to use the Dex VI fluid, but more reading tells me it came with the Dex III. While I might still go for the Dex VI I don't think I need the most expensive brands if it was already set up for the Dex III. I've read dozens of threads and posts about the old "this is better than that" opinions. PB wants to use Pennzoil, but I'd rather have Castrol if I do that through them. I'd just as soon use Supertech (approved by GM) for 1/2 the price if I have my son do it.

I just want to make sure I get ALL the old stuff out and put good stuff in. PLEASE: no amsoil ads!


It is hard to believe with all this internet forum info the word about the defective GM DEXRON III fluid is still unknown to some...no excuse to the repairs shops about this !

you are to use dexron VI this is the approved replacement fluid for your transmission...

the reason GM dumped this dexron III spec is they had too many repair claims on warrantee ...they tested the fluid in these damaged trannys and found high acid content...acid eats at the metal then NO GO !


I have been using synthetic in my 4L60 trannies since about 1998...guess what no tranny failures or leaks ..

dexron III is no longer a GM approved fluid ..this means you will not find any GM sec number on these containers of fluid...so who knows whats really in those bottles...

use mobil synthetic tranny fluid of the dexron VI spec....then you will feel the difference after a few hundred miles especially on cold temps below 20 deg f...faster shifting !

It is hard to believe with all this internet forum info the word about the defective GM DEXRON III fluid is still unknown to some...no excuse to the repairs shops about this !

you are to use dexron VI this is the approved replacement fluid for your transmission...

the reason GM dumped this dexron III spec is they had too many repair claims on warrantee ...they tested the fluid in these damaged trannys and found high acid content...acid eats at the metal then NO GO !


I have been using synthetic in my 4L60 trannies since about 1998...guess what no tranny failures or leaks ..

dexron III is no longer a GM approved fluid ..this means you will not find any GM sec number on these containers of fluid...so who knows whats really in those bottles...

use mobil synthetic tranny fluid of the dexron VI spec....then you will feel the difference after a few hundred miles especially on cold temps below 20 deg f...faster shifting !

I didn't know that about the DexIII. I looked at everything available and decided on Wally's SuperTech Dex VI for $3.77/qt. It sates clearly on the bottle that it is approved by GM for use...and since mine "only" had the Dex III originally I think it will be an improvement and should do fine. Besides, I really need that savings after the rear axle damage I found. :(

I didn't know that about the DexIII. I looked at everything available and decided on Wally's SuoerTech Dex VI for $3.77/qt. It sates clearly on the bottle that it is approved by GM for use...and since mine "only" had the Dex III originally I think it will be an improvement and should do fine. Besides, I really need that savings after the rear axle damage I found. :(

since wally's dexron VI has the GM spec on the container your good. that means the fluid is properly formulated..you will see a difference .it takes a few hundred miles.

mobil synthetic dexronVI is about 6.oo...