New GM Dexron III spec

[Dick in Falls Church]

Interesting article in Infineum Insight, a fuel and lubricant additives industy journal.

GM released the spec in April 03, and has now started approving fluids. Was going to be a Dexron IIIH, but trademark considerations made this unworkable. So, it will now be Dexron III labelled as "approved againsty the H specification".
Biggest difference is the minimum performance to pass the oxidation test. Dexron III(G) was run 300 hours, the H is 450 hours.
GM Transmission Fluid Group Leader believes the new specification will not cause radical changes in additive chemicals, but it is likely that they will preclude the use of most, if not all, Group I base stocks for ATF formulation.

 

[Eiron]

****,

Do you have any idea how this oxidation test compares to real-life use? If I simply calculate the distance using my car's average mph (as shown on its computer display), then this test only works out to be about 10k mi/1yr for me. This is quite a bit less than GM/Saab's recommended 60k mi change interval.

Thanks,

Greg

 

[Dick in Falls Church]

The oxidation tests I know of are GM THOT and Ford ABOT. They are run at specific temperatures (and whatever conditions) for 300 (old) hours--
now 450 for GM.

This supposedly equates to GM's 50,000 mile severe service drain recommendations (100,000 miles normal service).

Some other changes:

Cycling test Increased from 20,000 to 32,000 cycles.

Plate Friction Test: Increased from 100 to 150 hours and from 18,000 to 27,000 engagements.

Also adding an "Air Entrainemtn Test". Limits and conditions not finalized.

 

[Al]

Watch for GM transmission failures. They are probably seeing some kind of trend and have brought out a new fluid to head it off.m Ford did that in the late 70's when their cam shafts began to fail. They came out with a new oil. Of course they didn't fis canshafts that failed without this "new oil".

Oh..then there is the GM DexCool which was an attempt to head off the infamous Intake gasket leak

Sorry I am so untrusting.

 

[Dick in Falls Church]

Al-
Ford claimed it was the use of the wrong oil, but the failure also happened with AMSOIL and Mobil 1, neither of which fell into that category.

 

[Chris 2421]

This may be the new synthetic trans fluid that GM is now using in the Allison trannys.This fluid is made by Castrol,and the info can be found on the Allison website.

 

[Dick in Falls Church]

Chris,
Not the same fluid.

 

[sprintman]

I get Infineum Insight mailed to me here in Oz free. Interesting article this month on dieselisation in the US.