Quote Originally Posted by stocker View Post
I have a 2008 grand prix base model with 95,000 miles. I’ve owned the car since 30k miles and had the transmission flushed at around 50k miles. I made sure to ask if the fluid would be flushed or just the pan drop and top off – the dealer said no flush and then proceeded to flush it >:0

I have done a fair amount of trailering motorcycles and gear with the trailer and bikes probably nearing the tow max capacity of 1000lbs. I’ve estimated (on the high end) 9k miles of this type of towing.

Recently, I have noticed under light acceleration the shifts between 1 and 2 and maybe 2 and 3 have become slightly harder. Not jarring or anything but noticeable. It definitely does not happen all the time. I haven’t done a good job of noting when it happens (trans temp, outside temp, drive time etc).
I am planning to have the tranny serviced soon (not flushed!) and I’ve done some reading about potential solutions. Tranny cooler, shift kit are what I’m seeing but I wanted to see if anyone has any comments about my observations.

Do shift kits increase the heat buildup in the transmission requiring a tranny cooler? Would installing a shift kit without a cooler, and continuing to tow in the manner I have been, be a recipe for transmission failure? Would a transmission shop install a shift kit and or cooler or would they stay away from these "modifications"?

Anyone think I'm destroying my transmission? I generally run 215-225* over the long trailering trips with the highest I ever saw at about 230*.

Thanks in advance!
as a side note GP's were never meant to tow. Given that your adding all the weight and heat on you should have fluid replaced way more than you have, and especially at those temps honestly you should not break 200. The shift kit will help out but since youre screwed on tuning, I would higly recomend the shift kit and approiate cooler. There are tons of writeups on this site, and if you can figure out how to hook up a trailer you can service your own transmission. search is our friend best of luck