Hi, Newbie when it comes to towing. Our family just went on our 1st camping with our 2008 Suburban pulling a lite hybrid trailer (est. 5,000 lbs loaded). We live in Central California (near Fresno, CA) and we drove into the Sierra National Forest on Highway 168. The area that we go to (Wishon Dam/Courtright) is a favorite of our family and we camp there 2-3 times a year. Anyway, Highway 168 has a steep climb for about 2-3 miles and I was paying attention to the transmission temperature all the way up since i knew it was the steepest part of the drive. I had tranny temperatures near 240 degrees for during this stretch only. I was very concerned about the tranny temperature but not knowing if it would cause immediate or long term damage. I'd like to know when it makes sense to install a transmission cooler for towing. What's the max. temperature should i know when to pull over and let it cool? Is 240 degrees for a couple of miles OK or WAY too hot for the tranny? Also, what's my towing max? We plan on taking a trip in June 2013 to Mt. Rushmore and to the Grand Canyon later this fall and i want to make sure i'm prepared for our trips and that our suburban can handle it. Thanks........ P.S.......here's my VIN: 1GNFC16J18J219568 if that helps out.