I am planning a trip to the West Coast, travelling through the Canadian Rockies pulling our fifth wheel trailer. My question is, should I leave the transmission on automatic mode all the time, or should I downshift manually in the hills?
When I notice the engine starting to work harder and speed dropping off, I normally shift the transmission to a lower gear to prevent the engine from lugging. When going down a steep hill, it’s best to slow down at the top so the transmission can be shifted to a lower gear and then use the engine braking to keep your speed down. If the engine appears to be racing, use your service brakes to temporarily burn off some of the momentum.
Don’t keep the brake pedal depressed all the time, apply the brakes for a moment and then let up to prevent the brakes from overheating before you push down on the pedal again. Keep repeating this cycle as you go down the hill to keep your speed under control.
Apply the brakes for shortperiods of time, then let off. When you are on very steep hills such as the Eastern entrance to Yellowstone Park, you may find that you will have to shift down to low gear on the way up. As a general rule, I always use the same gear to go down a hill as the one I used to go up. Lower gears help the fan move faster to keep the radiator cooler.