Ideal Transmisson Temp

98, 130k, AW4, 35s, 4.56s, 10"x12" aux cooler mounted to the driver side front of the radiator, tranny temp gauge installed on the cool line.

- At what temp should I start to worry?
- As a general rule, what tmp was the fluid before it was cooled?

Thanks,

I always thought 180 was the ideal temp. for most lubricants, guess it`s a leftover from my motorcycle days. 180 was always the magic number.
Read a prospect for a tranny cooler the other day, said, tranny fluid starts to break down fast above 170. Didn´t make much sense to me, figure at the pump or right at the clutches, it was getting a whole lot hotter than that, during normal operation.
Used to watch my Chev., when the tranny was heating up (had a sender in the deep pan), it would also heat up the motor (coolant) even with a rather large tranny cooler, kind of a slippery slope, the motor and the tranny would heat up together and get to around 240 pretty quick, tranny fluid usually smelled burnt afterwords. I had the in radiator cooler and the aux cooler both hooked up. Took a fried tranny apart, much of the internals was burnt black and blue, I´d say it was well above 170F.
My XJ with the stock aux. cooler, doesn´t seem to heat up the tranny often.

Interesting. The cool side gets up to 180 at times, sometimes over that while driving on side streets. Guess that means the hot side is 20+ degrees hotter than that???