Dexron VI vs. Dexron III

[96oldsmobubble]

Hello,

I am getting ready for a fluid and filter change on my 1996 Oldsmobile Cutlass Supreme with a 3100, car has 140k miles, last service was done around 35k miles ago. I already purchased 7 quarts of Castrol Dexron III but was reading up on Dexron VI being fully synthetic and a cooler running fluid.

 

My question, is this worth the investment of switching to VI for a higher mileage transmission? I know a transmission cooler is a big help also; or should I keep the III and install a transmission cooler?

Thank you

[Night Fury]

Install cooler, go with dex VI. Dex VI was such an improvement over Dex III that they skipped IV and V lol

[xtremerevolution]

Install cooler, go with dex VI. Dex VI was such an improvement over Dex III that they skipped IV and V lol

 

What he said.

 

Yes, its worth it.

 

Sent from my HTC Magic using Tapatalk

[RobertISaar]

Install cooler, go with dex VI. Dex VI was such an improvement over Dex III that they skipped IV and V lol

 

truth. i've seen GM's clamied differences, and even if they overshot by 50%, it's still a vastly better fluid than dex III.

[96oldsmobubble]

Anyone used Castrol Mercon/Dexron? It says its equivelent up to III-H. The reason I am partial to this, besides already having it is that my Merc AOD can use it too! I do like what I have read up on the VI though.

[jman093]

Though everybody has already said it, here's GM themselves saying it:

 

http://www.sandyblogs.com/techlink/2009/05/dexron-vi.html

[RobertISaar]

GM's numbers for comparison to Dex3 from a TSB in november 2007:

 

 

 

fluid service change interval: same as Dex3; 100K miles in normal operation, or 50K miles in severe spplications

 

clutch friction stability: improved 100%

 

clutch durability due to fluid: improved 120%

 

oil film thickness: increased 20%

 

fluid oxidation: improved 100%

 

foam/aeration: improved 150%

 

shear stability: improved 200%

[slick]

Does it mix alright with Dex III? Meaning, when you drop your pan, you are only going to get about 1/2 of the fluid out of the transmission.

[96oldsmobubble]

According to that awesome article, the Castrol Dexron/Mercon I have was not tested by GM and therefore it is not called Dexron III which was discontinued in the mid 2000's. Just a multigrade which is going back to Autozone!

[96oldsmobubble]

I was kind of wondering the same thing, Chris. From what I have read about VI so far, mixing it with the III already in the torque converter is not harmful, just lessens the total effectiveness of the VI.

[RobertISaar]

the same thing could be said about almost anything... that's like having a gallon of milk that's half empty and then topping it up with pure chocolate milk.... of course it's not gonna be full chocolate milk, but it will still be better than just regular.

 

yes, i like chocolate milk.:laugh:

[wickedbuick]

I bought 12 quarts of dexIII for when I put my trans back in my Regal. I think I might use that on the Olds I picked up when I replace the trans on it instead. I take my regal to the track and drive it more agressively. The Olds I got with a bad trans and will use it for a second a to b vehicle when I fix it since my wife can't drive the Ion cause its stick. She doesn't have an interest in even learning at this point so thats why I got the Olds. No way she'll ever drive the Regal!! Well maybe in an empty parking lot hahaha

[tornado_735]

I only did a pan drop on my Pontiac, and replaced what I'd drained with Castrol Dex/Merc. I've not noticed any problems.