What oil should I use in my automatic transmission

[BoL]

Hi,

What oil should I use in the automatic transmission in my 1967 Buick Lesabre? the owners manual recomend "AQ-ATF" oilfollowed by a number and the surffix A, for example (AQ-ATF-XXXX-A) what oil is this? Is it possible to use Texaco Texamatic 7045E Dexron III oil? Hope you will understand my english, I'm from Sweden so my english are not the best.

[Guest sixpack2639]

Yes, you can use Dexron III but, once you put Dexron III in your tranny, you can not go back to Type A or Dexron II.

Cheers, Carl

[NTX5467]

In the USA, there are still some Type A automatic transmission fluids available. Some auto supplys might still have it as do many convenience and grocery stores.

The "Type A" transmission fluid spec was around for many years. GM's Dexron family of transmission fluids (first "Dexron", then "Dexron II", Dexron IIE", later on "Dexron III", and more recently "Dexron III, Specification H") replaced the "Type A" specification and GM states that the latest version of Dexron III is backward-compatible all the way to their first HydraMatic automatic transmission.

Dexron III is a much superior lube to the previous Type A spec. You can also check the Texaco website (USA or otherwise) to check the specific number of TexaMatic fluid available in your area and what manufacturer approvals it might have.

Enjoy!

NTX5467

[Guest oakland]

What do you mean by backward compatable? I have Dextron II in my Riviera. Would it be Ok to add Dextron III if I need to add fluid, or do I have to drain the transmission and re-fill with Dextron III?

[Guest sixpack2639]

Oakland, as I stated above, you can add Dexron III to Dexron II, Dexron IIE, or Type A, but the manufacturer recommends that once you start using Dexron III you DO NOT revert to one of the older fluids. Carl

[NTX5467]

As Dexron has progressed from the orig Dexron formulation, the basic viscosity and base stock of the fluid has probably remained pretty much the same, what HAS changed is the additive package as it has been upgraded to take care of certain situations that have come up over the years. Seems that the upgrade to Dexron II had to do with issues of the internal (to the radiator tank) transmission cooler becoming corroded and leaking?

Dexron II lasted for a long time, then was upgraded to Dexron II-E when GM did their first computer-controlled automatic transmission valve body in the 1980s. By observation, Dexron II-E seemed like it shifted a little crisper (in the Turbo 350 in my '77 Camaro) than the prior Dexron II did. Dexron II-E was sort of an interim fluid to the current Dexron III fluid.

I, personally, have not read that you can't replace Dexron III with Type A as a "fluid change" where the orig fluid was Type A. On the other hand, considering how much better the additive package and other upgrades are with Dexron III, I don't really see any reason to consider going back to Type A from Dexron III . . . . unless . . . there is something in the particular transmission (originally spec'd for Type A) that works better with the spec Type A fluid (I can't really imagine what it might be, but it's possible). I also like to use major name brands of these things too--personal pref.

There should be no issues with using Dexron III to add to existing Dexron II fluid. To me, using the latest version of the particular spec fluid is the better way to go, especially if GM's recommendation and approval for it goes back as far as it does.

Just some thoughts,

NTX5467