From what Ive learned here...

1) Tranny cooler is good idea
2) Some say cooler needs thermostat, some say not
Other..
1) Am based in Tassy, where winter is cold, (well below zero) summer can get to 35C
2) 90% of my driving is at 100kmh

My questions are :
1) Did the factory coolers come with a thermostat?
2) If not, was it because of their size? (IE...cooler was small enough to not overcool fluid)
3)Therefore, if I purchase a (relatively) small cooler, do I still need the thermostat?
4) Can anyone speculate why my (4sp non tip) has developed a noticeable THUMP when downshifting from 4th to 3rd when cold only? (Flushed 20,000km ago...car done 185k km)

Thanks.
JD

The factory cooler is just a line going through the bottom of the radiator. Since the radiator fluid will be close to the ideal temperature of the ATF fluid it will generally warm up the ATF fluid when needed too cold and cool it when too hot.
It is less than ideal and from my understanding not sufficient in keeping ATF fluids at optimal temperatures.

I think a thermostat is not necessary, but this means you need the right size cooler. Being your temperatures seems mild to cold, a relatively small cooler would be best.

Thanks for that Spetz.....
When I was speaking of factory cooler, I was talking about the factory Mitsi air cooled cooler (optional) that could be fitted as a dealer extra.
So in theory, an aftermarket cooler similar in size to the Mitsi one would be the obvious choice I feel...

When I was speaking of factory cooler, I was talking about the factory Mitsi air cooled cooler (optional) that could be fitted as a dealer extra.
So in theory, an aftermarket cooler similar in size to the Mitsi one would be the obvious choice I feel...
As I understand it, there was only ever a factory optioned ATF cooler for the 2nd gen (and maybe 1st gen) - there was no factory supported dealer fit cooler for the 3rd gen. Many people have fitted the 2nd gen kit and it is a good choice, but the mounting points were deleted from (I think) the TH onwards so mounting brackets need to be fabricated as well for later cars.

I tought all the 2nd gen auto's had the external cooler as well as the internal radiator one.