Can Dexron always substitute for Type A?

...

No.

Any Dexron fluid manufactured these days supercedes the Type A spec from

50 years ago by a long long way.

GW

As Geoff said, Type A is an obsolete spec and was superseded ages ago. Any fluid being sold as "Type A" today is best avoided as it could be pretty m uch anything. The current version of Dexron is probably the appropriate fl uid, but if the shift quality is lazy and soft with Dexron (and you're sure that the bands are adjusted correctly), you can try some Type F to firm it up (old racer trick.) The main difference between Dexron and Type F is th at the Dexron is a little more "slippery."

good luck,

nate

I am rather bemused that there are so many different types of AT/PS fluid. I wondered if it so dealer workshops can charge $$$ per litre for their special brew. I would think for hydraulic fluid, the main parameters are viscosity, temperature range, toxicity, and what seals or hoses it might attack. For aerospace, other factors like flammability and compressibility are an issue, but probably not for mass-market cars.

Dexron and Type F are very similar, the difference being the frictional cha racteristics. For years those two covered 90% of vehicles, the notable exc eption being the green Pentosin stuff used by Citroen, etc. (and very incom patible with traditional ATF, never mix them!) now you have special specs like ATF +4 because the trannys today are engineered so fine that they'll d ie if not fed fluid with very particular specs (and still may, at times...)

There really aren't any more. The thing is, automatic transmissions have been around for more than sixty years now, and over that sixty year period the designs have changed somewhat and improved a whole lot. So the same thing has happened to the fluids.

There are SAE standards, and most cars use fluids that meet the SAE standards, but the problem is sometimes with a very old car, the original standards have long been superseded and the problem is figuring out which oen applies.

--scott

The first fully automatic transmission was offered in late 1939 for the

1940 Oldsmobile, Hydra-Matic. Olds and Buick offered the semi-automatic, Safety Automatic Transmission beginning in 1937. Of course, Chrysler had the semi-automatic, Fluid Drive in 1939. I would expect that the fluids would have been perfected by now.