[svxistentialist]

Originally posted by lee
I've been interested in this topic, and have read some anecdotal evidence that says about 160F is the ideal. A paper from the automotive section at LSU says most automatic transmission OEMs don't try for TC lock-up until above 120F (of course ours is about 150F).

The only factory spec on minimum temp I've come across is from the GM truck division which says NOT to operate with dexron III filled transmissions below -13F (-25C). They suggest a pre-heater or let it idle until the ATF reaches that temp. I'm presuming that the fluid is too thick below that point to effectively flow to all the proper places (not stated in their paper).

Interesting topic. I am having a B&M 19000 lbs cooler put on mine, because it has just fried the second tranny since I've had it. Brake band and clutches burnt, lock-up fried[hence higher consumption]

Climate is temperate here[i.e. wet!] we never have the low temperatures you mention. My high temperatures are caused by stop-start city driving, rather than ambient problems.

Presuming the OE cooler is unclogged[later models without turbolator], in theory the original liquid/liquid intercooler is the better solution. The engine should lend heat via the radiator coolant to quickly bring the tranny oil up to optimum temp. A divert valve to shut off the oil from the additional cooler is a really, really good idea, and use the OE one in the rad for cold winter driving.

If this is not possible, as in where the original has been bypassed, then the old method of putting cardboard or some such in front of the new cooler is a very good remedy. Obviously be sensible, and only block off maybe half of the front surface, some cooling is required. Also don't forget to take it out in warmer weather, and don't come cryin back to me if the thing cooks because you forgot to remove the shield!!

Joe