I have a 2015 MDX that I need to install a hitch for towing my 4,000 lb boat. The boat will be towed in the midwest most likely up to 125 miles maximum distance. Do I need to or should I install the transmission cooler.
Yes. If you are towing you should install the cooler. The transmission is terrible and one should install the cooler even without the intention of towing or change the fluid every other oil change and do a 3x3 every couple of years.
They made this car with the expectation that 99% of the owners would not be towing. They even sent a whole survey asking me how this impacted my decision to purchase the vehicle - which for me had zero impact as I don’t expect to tow.
Acura specifies a standard towing capacity of 3,500 lbs for the 3rd Gen MDX. The capacity for FWD models is pretty much stuck at 3,500 lbs, but the capacity in SH-AWD models can be increased to 5,000 lbs when the ATF cooler is installed.
It sounds like you'll be doing this somewhat frequently in the warm months, so I'd say install the cooler. My dealership quoted me around $10K for installing a new transmission, so I would think it's a good idea to spend a couple of hundred (or less if you DIY or go aftermarket) on the ATF cooler.