[VAL] Trans temps

[Stan Nicholson <stan@xxxxxxxxxxx>]

Ed and Joann - The temp reached and the duration affect what's 
essentially an oxidation process (if I understand correctly) that 
degrades the fluid's ability to lubricate and protect internal trans 
components. So there's not a magic point at which the fluid changes 
from great to lousy; it's a process that occurs over time. There are 
the traditional warning signs of dark/dirty fluid on the trans 
dipstick, or (worse) a burnt smell when you sniff the dipstick. 
Unfortunately the first sign that you've pushed the fluid's 
capabilities typically is a failed transmission.

 From what I've read, Ed, if your temp stays below 200 almost always, 
then the 30,000 interval should be fine. If you do get in a situation 
where the temp stays above 200 very long or especially gets 'way 
above 200, I'd put a trans flush on my do-it-pretty-soon list.

A reason GM may have for not including a redline on their gauge is 
that they don't want to imply that it's OK to run elevated temps that 
are just below redline.

Joann, there's probably a way to have a computer or purpose-built 
diagnostic device (really a special-purpose computer) monitor the OBD 
port on your tow vehicle, to log what the sensors are reading and the 
durations thereof. But I doubt that the info is really worth the 
effort. For practical purposes, it's sufficient IMHO to use the rough 
rule of thumb above. That does presume, though, that you a) actually 
have a trans temp gauge, and b) do watch it while you're driving. . .

Stan