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Switched from Dex 3 to Dex 6.

Discussion in 'Chevy Trucks' started by Newdude, Jul 24, 2010.

  1. Newdude

    Newdude Senior Member
    Messages: 889

    Well, I changed my transmission fluid right around 50k. Threw out the Dex 3, and in went the Dex 6. It drives smoother since I did it as well. One thing I did notice however, is that it doesn't seem to run cooler. The

    past few weeks its been running right near 130-160, no matter my driving. It can run 150 going to work (15mi on broken highway, about 6 lights, speed limit is 55mph). It can run 165 around town. I dont drive it

    hard. Usually manage just fine with a good foot and keep it under 2100rpm accelerating. Occasionally, I will push up to 2500rpm (when I feel the need to unleash some more ponies). What am I missing that it runs,
    in my opinion, so hot? Too much dirt or something in the way of the cooler? Is it just the weather and the humidity? Its been in the 80's and 90's for weeks here, typically with high humidity levels.

    I recall this past winter it would always hang around 120 or less.

    Am I just crazy maybe? :dizzy:
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Were you expecting it to run cooler with Dex6? Hope that wasn't you're primary goal as it won't help. And by your description it doesn't need too, if you average temps are around 170* it's about as perfect as it can be. And yes the noticeable increase in trans temp is due to the warmer ambient temps, totally normal there too.

    But next time avoid the Dex6, there's much better fluid choices in the aftermarket for the 4L80E for comparable cost if that's what you're after. Statistics have shown it's far from what GM claims it to be for the older non clutch-to-clutch transmission such as the 80E's for which is wasn't intended directly for, but for a substitute to replace the previous Dex3.

    Just because it's relativity new doesn't mean it's better....
  3. Newdude

    Newdude Senior Member
    Messages: 889

    No, running cooler was something I didnt expect. Maybe its because I bought the truck when summer was coming to a close?

    What fluids are better than Dex 6 by the way? When I had it changed, I did it at the dealer I am at. It was a demonstration by the Castle Chemicals, a local distributor of all sorts of automotive products, so it was a freebie. I didn't run any of those additives that go in every exchange/flush we sell.

    If there are better products, would it be a dumb idea to switch? If I did switch, I think I will add a pan drop and filter change to the mix as well.
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Then don't be too concerned with the warmer temps you're seeing, they're simply the byproduct of the warmer ambient temps you're under now and 170* in those temps is nothing to be concerned about. When it's running 220* empty and 250* loaded then it's time to worry.

    Both Red Line Oil and Mobil 1 make outstanding synthetic Dex3 classified ATF's that have well proven to be all they claim over the years. In fact when a customer requests a refill with synthetic (or even in my own personal vehicles) that's all I use any more. Either one will put Dex6 to shame under actual usage conditions. You'll get the smoother operation that you noted with the Dex6 but you'll also get all the benefits that come with a premium fluid as well.

    As to whether to change it out even though it's fresh that's your call. It won't hurt anything persay, just depends on what you want out of it and if you're looking to prolong the life of the trans (and improve it's performance) as much as possible.

    Curious, what additives are you selling with a trans service at the dealer?
  5. 70monte

    70monte Senior Member
    Messages: 468

    Years ago I tried Mobil 1 synthetic tranny fluid in my 98 K1500 with the 4L60E and it didn't like it at all. The tranny felt like it was slipping all of the time and at the time, I only had about 20,000 miles on the truck if I remember right. I went back to a conventional Dextron III and no more slipping. I haven't used it since.

    I did use Valvoline Dextron VI in my 2004 Monte Carlo SS when I changed the tranny fluid a few months ago. I could tell a little difference. The tranny seemed to shift better but I think this was its first tranny fluid change with 90,000 miles on the clock.

  6. Newdude

    Newdude Senior Member
    Messages: 889

    Sounds good. I think I will look into those two a bit more.

    As far as the additives we use, see the two links below:


    http://www.castlepackspower.com/Catalog/ChemParts/tc8.html We use TC-12 (dont think 8 exists)
  7. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,525

    Some dex 6 Is synthetic some is not.I like the valvoline synthetic dex 6. Works great in all of the flushes I have done.
  8. 70monte

    70monte Senior Member
    Messages: 468

    From what I understand, the GM Dextron VI is a semi-synthetic and Valvoline Dextron VI is a full synthetic. I was a bit hesitant to use it since I have not had good luck with synthetics in vehicles that didn't originally come with them.