Hello All - I'm going to be towing a waverunner beginning next year and I'm looking into purchasing/having installed a second transmission oil cooler. I don't plan on doing any extreme heavy-duty long haul towing, (Waverunner and trailer = 1100lbs and will travel 3 hrs at most NJ to PA). I live 10 minutes from the Atlantic - Ah the joys of NJ! My question is Will the medium duty cooler be good enough or should I get the heavy duty? I'm not sure and I would rather have too much that too little but I'm unclear if having too much is detrimental. Any and all help is greatly appreciated.

 

Too much cooling can be a bad thing since the fluid expands as it heats (crucial to level control) and the clutch-packs have an optimal fluid temperature specification where they will have the most grip and least wear. Unfortunately most transmissions do not have oil/ATF thermostats like many engines with external oil coolers do so you can over-cool it. I know some BMW's do though.

The best setup would be to monitor fluid temp with an advanced scan tool, under normal driving conditions. Then build a cooler setup with a thermostat that opens at that same "optimal" temp. It won't be the easiest or the cheapest route... but it is the "right way".

Regards,
Justin