Deciding between 2015 Sierra & Silverado (1500) Help!

Big Whiskey · February 6, 2015

Unless you're driving in snow/ice, then you should probably just have the transfer case in 2HI instead of Auto. Some people argue that driving in Auto when you don't need it just puts more wear & tear on your front end components, and reduces your gas mileage. While towing, I like to use tow/haul mode, and put the transmission in M5 (sometimes even M4 if I'm in a lot of hills). Tow/haul mode will improve the shift firmness and engine braking...and holding it in 5th gear will keep it from gear hunting as much. These engines don't have much torque in the lower RPM range, so they need to rev a little higher when towing to maintain speed on the highway. It's normal, especially on hilly roads. And, it's actually better for the truck to pull a hill at like 3k rpm's the whole time in 4th gear....than to start in 4th at the bottom of the hill, then shift to 5th half way up, bog the engine down, then downshift again and start the process all over. All that being said, if you're looking at a new truck with the 6.2 engine, it will have the 8-speed transmission...which I don't have any driving experience with...

redwngr · February 6, 2015

I have two "nagging" questions - first - with my old Sierra, when towing up highway hills going 55 mph, my rpm's would stay "stuck" high and the truck wouldn't ratchet down or seem to change gears in automatic mode. I had a lifter replaced and was also told to NEVER keep the truck in "Auto" vs. 2 high esp. when trailering. (one GMC tech said they HATE the "Auto" control (vs. keeping truck in 2 high all the time). Should I have been using the "manual" mode when trailering?? Also, one poster mentioned the Sierra has "real aluminum trim"...and Silverado doesn't. So Aluminum vs. what? And does this make a difference in quality? Thank you!

Auto is a waste of fuel, since the transfer case will be turning, even though the front axle is not locked to engage the wheels.

Todays computer controlled engines and transmissions are MUCH better at selecting the correct gear to be in. Combined with more gears available (6 or 8) and higher torque/hp engines they do a much better job of not 'racing' unnecessarily.

If done limited towing with the 6.2/8speed so far, but pulling the enclosed trailer on the freeway at about 65 (with the cruise engaged) it would sometimes downshift to 7 or 6 (and I think once to 5th) but it never seemed to be 'stuck' at high rpm.

If your trailer is not wide, trailer mirrors may not be necessary. On the other had, the only time I didn't like them on my previous trucks was when parked in a busy lot. I'm still debating about retrofitting them to the current truck (or trading again to a max tow).