Dexron III vs Dexron VI -- reading that VI may cause hard shifting?

[gladesteen]

Hi gang,

Its time again for my trans fluid change. Last time was definitely Dexron III, but now i understand the fluid recommendation is "new" Dexron VI.

I've read a few forums/threads saying that switching to the "new" Dexron VI caused harder shifting, but once they switched back to Dexron III the hard shifting went away.

Anyone have input on this?

I'd like to go with the "new" Dexron VI, but if its going to cause issues, maybe i should stay with the Dexron III........what do you think?

I have a 2004 Olds Bravada --- Final 500 model


Thanks,
Mark

 

[Reprise]

Personally, I like a little firmer shift, myself. If they said 'harder', and not 'harsh' - I know it's probably semantics, but I'd be fine with a little harder than stock, especially in a truck. Our 4L60s, descendants of the 700R4, have never been known to be 'firm' shifters - especially once you get past the 1-2.

Think of it this way - if it shifts more firmly (within reason), you're getting a more positive engagement on the clutch packs, with less slippage - meaning longer life.
Finally, given the amount of people here who have Dex 6 in their units, and I haven't seen complaints about increased shift firmness - I think it would be worth switching - it's supposed to be way better spec than Dex 3. I have Valvoline Dex VI synth in mine, and no complaints at all with it (other than maybe price...but since this gets left in longer than motor oil, I think it's worth the spend)

Provided you have a good source of Dex 3 (is anyone still making it?), you could always switch back if you felt *that* much of a difference with the VI vs the III

 

[gladesteen]

Reprise, thanks for the comment. I already have a "firm" shift due to my ECU program upgrade. Definitely dont want it any harder than it already is.....which is why i'm asking this question.

I appreciate that you ARE USING VI right now and not having any issues. As i searched around, it wasnt overwhelming that people had adverse comments about using the VI fluid. I'm basically doing a sanity check.

Thanks again,
Mark

 

[Reprise]

Given that, I'd definitely go with the VI. GM specs it in place of III, and they haven't recommended III in several years. Since you've increased your line pressure w/ the ECM flash, I'd go a little farther and recommend a synth. Since you had that done, I'm guessing you're not afraid to get on it a bit, and if you're changing fluid, you're planning on holding on to her a bit longer.

 

[gladesteen]

Yes, looks like VI it is!

From what i've read, all versions of VI are synthetic.

The best prices (ive found) on Amazon are a 1 gal of AC delco with add on 1 qt for approx $40 for 5 qts. There's another deal for Mobil 1 VI - full case - 12 qt bottles for $61 shipped. I might do the Mobil 1 deal and Craigslist the second half for $30....something like that.

 

[Reprise]

Except for TC fluid, I don't think you gain anything by using AC Delco fluids. $20 extra for double the qty? (and enough to totally replace ('flush') the old fluid, btw.) That's $5.08/qt shipped (and 12qts ain't cheap to ship - ask me how I know . You can't beat that deal.

The other thing is...that'll be the last time you ever have to change the fluid in that truck. Get a good filter kit (I like Wix, myself), and you'll be done.

Oh, and if you do flush out the III (see the posts / videos referenced on this site) - I'd personally pick up 3-4 extra qts - the trans takes exactly 12, and you'll likely go through 12+ to refill it - if nothing else, you can keep a bottle to top off with, and return the extra. Just make sure you have +12 to start. Good luck!

 

[gladesteen]

Thanks Reprise!

I was thinking the same......seems getting 12 qts of good Mobil 1 for $60 is a great deal.........to me anyway.

Thanks alot for your input and help, really appreciate it.

Have a great 4th weekend!

Mark

 

[Mounce]

I got havoline dex-vi when I did my flush/service/cooler install a year or so ago. 12 quarts was a hair under $50 shipped from Amazon. Unfortunately they're out of stock now, just checked. Used an ACDelco filter if that matters to you.

12+ ~1 to 4 is correct for a DIY flush (search, there's a thread here on it) on these.

I do notice a hard 1-2 shift when cold but I chalk that up to the usual issues these transmissions have. Can't remember if it was or wasn't there before service. However I also recommend the VI. It is a better fluid.

Any fluid with the name DEXRON VI on the bottle is fine to use, all that have the name are supposed to have been tested and have passed/surpassed the tests for equivalency by GM. If they fail they can't use the name. There's also a website with a list of all registered fluids online, I don't have the link now after a phone swap but I found it on bobistheoilguy.com.