What to do?

[Paul S]

My 1988 Corvette calls for Dexron II transmission fluid. As near as I can tell, they don't make it any more.

[Cadillac Jim]

Dexron VI is probably backward compatible with your transmission. It's a THM 700R4, which was used through 2010 in various applications as the THM 700R4 and 4L60, and with electronic control as the 4L60E and 4L65E.

To be sure, I would call GM Customer Relations for Chevrolet at (800) 950-CHEV (-2438) and ask about your car. Have the VIN ready when you call.

Dexron III is almost certainly backward compatible. Several people make what they call Dexron III fluid but there really is no such thing because GM stopped licensing (and controlling vendor products to specification) at the end of 2006, but there is a current Dexron product (one of the manual transmission fluids, I believe) that is really re-named Dexron III. If all you need is to top off after servicing, this is probably your best option, even if Dexron VI is compatible with your transmission. I'm sure someone will chime in here and say which Dexron fluid is "really" Dexron III.

If you are doing a flush, or are changing the torque converter, or anything that involves changing 100% of the fluid, and your transmission is compatible with Dexron VI, you can get more consistent operation for cold shifting and 130% longer clutch life with Dexron VI. But if you are just topping it off without draining the torque converter, you won't notice the difference.

[JohnnyG]

A little more info:

http://en.wikipedia.org/wiki/DEXRON

http://www.gmpowertrain.com/VehicleEngines/DEXRON-VI.aspx

[cdgrinci]

Per the label on a bottle of Dexron VI (I did a drain and refill on my '04 Bravada); it stated that Dexron VI was compatible with Dexron II and Dexron III. The bottle I had was SuperTech (Walmart) brand. I also have a bottle of GM Dexron VI and it stated it was compatible with Dexron III (didn't mention II) but seems it would be.