Silverado trans cooler upgrade?

I previously owned a GMC 2006 5.3 and towed a 27' TT. I would regularly go over 200 (210+) when hauling over the mountains in western Virginia. It bothered me so much that I did have an additional transmission cooler installed. It went in front of the radiator, in the lower passenger side so as to not block the radiator. I did notice a fairly big difference. When temps did get high, they dropped much quicker. I thought it was a good investment.

However, I ended up trading that truck in for my 2008 GMC diesel, which hauled that TT over the mountains like it wasn't even there.

My 2010 Silverado doesn't have an external trans cooler, only the internal trans cooler in the radiator.

Normal driving and not towing its around 170 I think. Towing, it stays between 200 and 210. When I went to PA, there was one very long, very steep hill and it hit 237 and I was only going about 40mph. There were actually a few pickups pulling mud bogers on the side of the road. Looked like they were "cooling off." I slowed down to 35mph after seeing them, but it was still 230ish... My water temp is always at 210 all of the time (towing or not) except on that hill it went to 215 or so.

I think upto 220 is fine, I wouldn't worry about it at 200.


There are many debates about that chart that is floating around vs modern transmissions.

I have a 2007 2500HD with OEM cooler and a 6.0L. I tow a 6K TT. I have hit 200 in the mountains here in ID. But it generally runs around 160-170 depending on outside temp. You don't want to cool the fluid too much as hyd. fluid operates best when warm it also is able to relieve it self of any moisture that may be in the fluid. It may be you could use a larger engine or lower gear ratios if your trans temps are too high.

Your truck is an easy upgrade to a B&M stacked plate cooler. I made the swap on my 2007 6L90E trans. I used the original cooler lines and only had to make one new bracket. I bought the fittings to mate to the GM quick disconnects. Pulling a 9,000 pound 5th wheel I saw 210 plus degrees. After the swap, I have not gone over 185 degrees even on 6% grades. I found that it took longer to remove the grill than swap the cooler.

I expect the transmission fluid temp to be 60 degrees hotter than the ambient air temperature. The trans is OK with fluid temp up to 220 degrees though even on long grades in 115 degree whether the highest temp I have seen on my Allison transmission is 178 degrees. The absolute maximum temp is 262 degrees before the fluid will fail to function properly in the transmission.

The Tow Haul mode is designed to keep the transmission's operating temperatures as low as possible when doing heavy towing or hauling.