In addtion to the tripometer I can select to view transmission temperature on my 2008 Silverado with the 5.3 liter 8 cylinder. Just driving down the highway, without towing anything, I saw it at about 199 degrees. My question is: What is normal and at what temperature should I become concerned? Should I expect higher temperatures when towing my boat, in the summer, uphill? Thanks for any direction or advice.