I have a 2008 Suburban LTZ with 30k miles. It has the factory HD towing package which includes 3.73 gears, air suspension (love this), and a tranny cooler.
The truck tows fine to the local ramp, over moderate hills, etc. But on the longer tow trips over big, long grades it struggles. Last year on the way to Shasta I saw the tranny fluid go up to 235 degrees.
We are headed back to Shasta in a few weeks and I'm not axious to see this happen again. Back then I was towing in 'D' and I've since switch to towing in '3' which seems to have helped.
In addition to flushing my tranny fluid, now I'm wondering if it would be beneficial to swamp out the OEM tranny cooler for something a little beefier.
Will this help?