I'm about to install a transmission cooler in my Q45 and really want to know the temperatures before and after of the installation. Please let me know if you know of an OBD2 software that reads the automatic trasmission temperature. Thanks!

the RE4 tranny just has a simple sensor that basically tells the TCU when its "cold" or "hot" or "too hot"...

I would just install a digital gauge somewhere and you can monitor it seperately..

Consider that the rear planetary gets ATF from the cooler directly so measuring the change in the return line temp might be better than the sump temperature..............also the input to cooler is from the TC so the most extreme heat.........from the TC slipping.

The reason for synthetic is to increase ATF tolerance for those peak occasions.

As a side note........with 28,000 miles [in 14 months] on my conventional ATF [plus mixture of BG additive and Lubeguard]......lots of idling and city driving [plus 60 miles per day at 70 mph]........my ATF has almost lost all color [washed out very weak red].........Flushing this morning.

I've been bad to let it go so long [Tranny #3 was installed at 235k, 55k ago 3 years.....just turned 290,000 miles

ATF color is a great indicator of heat/overheat.

Brake pads, rotor trueing, brake fluid flush, o2 sensors, oil change, new tire on newish rim, tranny flush, diff flush.........lots to do this morning in 3 hours.

Back to ATF temperature, a heat exchange is lucky to drop ATF temperature 20F in summer and less in idling where the AC condenser is heating the already 120-130F ambient [hot air from car in front] to 150-160F............but that is sure better than 185-220F coolant.