Stay with Dexron 3 or go with Dexron 6

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On my 1994 Astro I am going to do a pan drop & filter change, should I stay with Dexron 3 or go with Dexron 6? Is it ok to mix the two? I have heard of horror stories about a flush on these transmissions, true or not I would rather just drain the trans. a few times and refill until all is clean. At Walmart the price for 6 is just a little higher than Dex 3. Is SuperTech OK to use? sorry a lot of questions bit I would like your input as I want to keep this van for a long time.
 
You can mix, but with a vehicle that old, I would recommend trying to not get a back spec'd fluid and get one that is only D-III compliant. They are out there. I recently bought some for 2 vehicles which spec D-III (not D-VI)

I would assume any brand is fine as long as it meets spec.
 
Supertech DexVI is an excellent fluid to use, plus its a lisenced GM fluid so it meets GM's standards.

Note, check on the bottle for the lisence number. Pretty awesome.

I'm doing DexVI drain/refills every 5,000mi. Good if you are DIY'ing it.
 
Just a note that some older cars experience unusual symptoms with dexVI.

But we use it in many, many GM trucks with no problems at all.
 
Yes I DIY, won't trust any shop. One other question, what about Lucus Transmission fix, any good or just hype?
 
I recently did the same job on my '89 astro. I used Valvoline fully synth DexVI and lubeguard red. It has done a fantastic job, went from having tranny issues to something that works just fine!

I did fit an aux cooler at the same time with an in-line magnefine filter.
 
If it were mine I would do a pan drop and filter change with good filter like Wix, put in Maxlife Dexron and Lubeguard, and repeat the fluid change without filter change in 10k miles. Some older vehicles dont like a complete fluid change.
 
Last edited:
Originally Posted By: Bluestream
I would go with Mercon V just to be safe...Who wants to have to drain out good ATF if its doesn't work well.

He means Dexron VI.

There is not a single licensed DIII product on the market. You may get a wide range of qualities.
 
Stay with Dexron III , it is what the trans was designed on. I have see several customer complaints of shift problems going from Dexron III to VI. I would suggest using Valvoline Maxlife Dex/Merc.
 
Originally Posted By: Thax
Stay with Dexron III , it is what the trans was designed on. I have see several customer complaints of shift problems going from Dexron III to VI. I would suggest using Valvoline Maxlife Dex/Merc.
Maxlife Dex/Merc basically is a Dexron VI fluid, look at the the specs. It would be my fluid of choice though for this application.

Supertech, either one you choose, is fine though.
 
My 1996 4L60E trans in my Buick was switched to Dex VI long ago and it seems to love it.

My 2001 4T65E in my Grand Prix seemed fine at first but I'm questioning if some of my problems are related or not. I ran Dex III (M1) for the first 90k miles and I'm nearly done with the next 90k miles of using Dex VI. I think I'll try Redline D4 next time. My TC can't always decide if it wants to lock up and I've also had issues with harsh shifting due to a solenoid issue that was resolved mostly by a shift kit. Both of those issues are common with this trans and most likely are not fluid related but I'm going to try something different next time. The M1 was severely sheared down in the 5.x range so I can't believe a thinner Dex VI would be much different if more shear resistant than the M1 Dex III. The new VI is thicker than the old M1.

I will continue to use the Dex VI in my wagon with the 4L60E.
 
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