So I have been towing a 20 ft travel trailer that weighs almost 4k loaded out, the dry weight is 2850. Towing the camper the is the whole reason I got rid of my Rubicon, the fam wanted a camper and I still wanted to be able to go offload on our trips, so thats were the 4runner came in. I live in eastern KS and all of our trips have been out west to the mountain states. I pull this boat anchor through the western KS and eastern CO winds. I have found that my trans temps directly corilate to wind and outside temp. I am running the stock cooler plus a Derale stacked plate 19 row cooler after the factory setup. This has helped my temps but not fixed the heat issue. On my first trip towing I only had the stock cooler and my temps got close to 250 at times (not sustained) while pulling in a head wind. This trip took us from KS to Yellowstone then up to Glacier Nat Park. After the trip I noticed the some funky shifting at random times (hitting hard going into drive and shifting). I took it to the dealer and had them do a complete flush, the tech told me the fluid definitely smelled burnt and the flush fixed the funky shifting issues.
Before our next rip I installed the second cooler and found that it helped quite bit. The thing is, the last couple trips I have managed to avoid the 40 mph winds of western KS either by luck or by driving at night. On those trips trans temps stayed in the 150 range and the 4runner pulled like a champ, I frequently looked down and found I was speeding and had to slow up. On our last trip back last month I hit the wind hard, outside temp was around 102 with a 40 MPH crosswind. I have always towed locked out in 4th no matter the conditions, but I didn't have enough power in 4th to sustain speed and the 4R would downshift to 3rd causing the trans to heat up. I have the torque app set to alarm if the trans temps reach 220. I had it hit 220 multiple times for a few secs before it would shift back to 4th then cool back down to 190 or so. Im noticing some funky shifting again like before so should I change the fluid myself and put a synthetic type trans fluid in or should I go back to the dealer and have them put World ATF in? I have been saving up for a rear bumper but I think that will go towards a re-gear and locker (4.11 possibly 4.30). I want this truck to pull good and not explode a tranny because I actually really like it and have been very impressed with what it will do off-road for what it is. Im currently running 285/70 BFG KO2 with a Relentless front bumper and sliders. Would a synthetic fluid disperse heat better than OEM and would a re-gear actually help with stress on the trans. Im all ears on this and I'll put up some photos of my setup including the second cooler. I would highly reckoned to anyone towing a camper or enclosed trailer to add a second cooler, it will only help to prolong the life too your trans. Forgive my photo posting skills, I suck at it.
