What Transmission Fluid?

[SpotOfTea]

Sorry first post here. My local dealer is being a jerk.

I have a 2003 GMC Sierra 1500 HD 6.0.

I recently drained and refilled the transmission with below which seamed to be within the specs of the owners manual. I had some from a SUV I had in the past.

https://www.amazon.com/dp/B00T96Q9A6/ref=dp_iou_view_item?ie=UTF8&th=1

It's always had a bit of a whine since I got it hence why I tried to replace the fluid.

But then when i was looking up online about the whine I saw that I should be possibly running Dexron VI instead and that GM had updated the specs.

Can anyone help clarify things for me I am new to DIY.

Thanks

 

[jake111]

I'm pretty sure you found the spec in the owners manual was for Dex-III and the Castrol certainly meets that spec.  I don't know about the GM transmissions since I have the Allison in my 2004.5 Duramax.  For the Allisons in that time era, it was found that the so-called compatible Dex-VI was not compatible with the Allison seals.  If your transmission seals are compatible (you'll have to research that), the Dex-VI is fine.  But that doesn't mean it's so much better than the Dex-III that it's worth changing out.  If you're trying to replace most of the old ATF then it will probably take at least one more drain'n'fill.  Each change probably only gets about half of the ATF replaced.

[CamGTP]

GM did update the spec but I only run Dexron 3 in the older vehicles like that still.

[Formulabruce]

I only use Dex 3 compatible, and ALWAYS re use the original Rubber pan gasket on the 4L80E.

the aftermarket gaskets are folded paper. ter originals are rubber with metal inside and very durable.

Im not sure the 1/2 ton HD gets a 4L80 though...

[davester]

Yeah, you want to use a DexIII fluid.  DexVI is supposed to be backwards compatible with it, but at least for some transmissions/transfer cases, they leak after switching.  If the unit has been rebuilt since it was manufactured (and after around '06-'07), then the seals likely have been upgraded to work with DexVI.

 

For my truck (which has a '06 transmission & transfer case now), I put DexVI in the transmission, but DexIII in the transfer case...

[elcamino]

This was put out by GM service........Dealers are not always the most reliable source for information. 

Quote

This information applies to 2007 and prior GM passenger cars and trucks.

Dexron III is being phased out as a product name. It is being renamed Manual Transmission Fluid and carries p/n 88861800 U.S. (88861801 Canada).

If fluid p/n 88861800 U.S. (88861801 Canada) is not yet available when servicing a manual transmission or transfer case, Dexron III can be used in its place.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Unavailability of manual transmission fluid part number 88861800 U.S. (88861801 Canada).

Recommendation/Instructions:
If fluid part number 88861800 U.S. (88861801 Canada) is unavailable when servicing a manual transmission or transfer case, Dexron III can be used in it's place. DO NOT use Dexron VI in place of the manual transmission fluid in any manual transmissions or transfer cases as a failure may result.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

Quote

MANUAL TRANSMISSIONS / TRANSFER CASES and POWER STEERING
The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle that previously required DEXRON®-III for a manual transmission or transfer case should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid.

 

Edited December 3, 2021 by elcamino

[Black02Silverado]

It will not hurt anything.  I switched over to AMSOIL's ATL transmission fluid when I had my 2002 Silverado and no problems and sold it with 200k miles on it.

 

Maybe my switching over early helped.  I switch all vehicles over at 10k miles to AMSOIL when bought new.  Dexron VI wasn't out then but as soon as it came out I switched.