Conflicting Info - Dextron III / VI for M1165

[Diablo]

I've just picked up my new-to-me 2007 M1165 w/ SN 246658. I've been reading through TMs, and have found where some say, "Use only Dextron III. Using any other fluid will damage transmission." However, TM 9-2320-387-10 (Operator's Manual) says it should use Dextron VI.

I've spent the last 2.5 hours combing through the forums, and in no closer to finding an answer. Any help, with citations, would be greatly appreciated.

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[Mullaney]

I've just picked up my new-to-me 2007 M1165 w/ SN 246658. I've been reading through TMs, and have found where some say, "Use only Dextron III. Using any other fluid will damage transmission." However, TM 9-2320-387-10 (Operator's Manual) says it should use Dextron VI.

I've spent the last 2.5 hours combing through the forums, and in no closer to finding an answer. Any help, with citations, would be greatly appreciated.

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.
The way to know for sure what is in your transmission is to draw an oil sample and send it to a company that can give you a solid answer. There are lots of options. Blackstone Laboratories, Inc. in Fort Wayne, Indiana is one place to look at. Try searching "blackstone" and you will find several discussions about their services.

Other than that, Dextron III was the oil at the time. Dextron IV came along a little later, then 5, then 6. Supposedly the higher numbers are backward compatible with previous versions... Given the opportunity, I suggest that you have your oil looked at then put more of the same in it when the time comes for a change or to top off your fluid.

 

[Mogman]

The common consensus is it is OK to use DEX VI in the transmission, but not in the steering or T case, that is for DEX III
You should not worry about what fluids are in it because you should immediately change ALL fluids and filters unless it has been recently serviced by a reputable mechanic that knows HMMWVs, if that is the case then confer with him/her.

 

[Diablo]

Mogman,

Agreed on changing all fluids and filters. That's what I'm working on.

So, I should disregard TM 9-2320-387-10 saying to use Dextron VI in the TCase and Steering, as well?

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[MarkM]

Dextron VI came out in 2006 and can be used to replace II and III. For me I would just use III as that is what came in our trucks. Just my two cents.

Mark

 

[Diablo]

MarkM,

Is Dextron III the original ATF in a 2007 truck, though?

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[Mogman]

The problem is DEX VI is a full synthetic and tends to make the steering system leak, this has been reported my many folks.
If it were me I would go with DEX III all the way around, but that advice like all others is worth exactly what you paid for it!!
EDIT, when the military went to DEX VI they just used it in everything, they have mechanics to take care of the little problems.

 

[MarkM]

The transmissions in 2007 have not changed in years so I can in no way believe they came with anything else but Dextron III.

 

[Mogman]

The transmissions in 2007 have not changed in years so I can in no way believe they came with anything else but Dextron III.

You are probably right, but if it got serviced later it could easily have DEX VI in it now., since GM claimed DEX VI was backward compatible with the earlier formulas I would be surprised if the GOV did not use DEX VI in everything after that point.

 

[Action]

9 years and 23,000 miles later, I have had no leaks with dex vi.

Was there ever a dex 4 or dex 5? I think they messed up the roman numerals and used vi instead of iv .

 

[Diablo]

9 years and 23,000 miles later, I have had no leaks with dex vi.

Was there ever a dex 4 or dex 5? I think they messed up the roman numerals and used vi instead of iv .

Are you running Dextron VI in everything, or only the transmission?

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[Coug]

Not sure when the military switched over to DEX VI from DEX III, but if it's a 2007 truck, then at some point it should have been serviced.
As others have said, DEX VI is supposed to be 100% backwards compatible in automatic transmission applications, so there should be no issues using it no matter what your truck started with.

 

[Action]

Are you running Dextron VI in everything, or only the transmission?

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I have dexron vi in everything that calls for dexron. In an REV truck.

 

[Mogman]

Not sure when the military switched over to DEX VI from DEX III, but if it's a 2007 truck, then at some point it should have been serviced.
As others have said, DEX VI is supposed to be 100% backwards compatible in automatic transmission applications, so there should be no issues using it no matter what your truck started with.

Just me flappin my lips but,,, GM also said their "new" DEXCOOL was backwards compatible, then they lost 10s if not 100s of million dollars replacing/repairing vehicles, replacing for example a pot load of intake manifolds their "backwards compatible" DEXCOOL dissolved...
Just saying!!

 

[Coug]

Just me flappin my lips but,,, GM also said their "new" DEXCOOL was backwards compatible, then they lost 10s if not 100s of million dollars replacing/repairing vehicles, replacing for example a pot load of intake manifolds their "backwards compatible" DEXCOOL dissolved...
Just saying!!

it's been long enough now that DEX VI is probably safe enough, as it being used in automatic transmissions is one of the few things they haven't had to repair in the 16+ years it's been in widespread use (at least that I've heard of)