I had an idea today. I frequently travel on roads where the speed limit is 35-40mph. For the sake of today's discussion, the speed limit on the road I traveled on for quite some time was 35mph. It's a long residential road with a few rolling hills and usually very light traffic. There are a lot of roads in the towns around me that fit this description.
I found myself cruising along in very light traffic around 40MPH and noticed that I was in 5th gear.
After a little fooling around I found that 5th gear runs from ~36mph to ~49MPH under light throttle while cruising.
I was getting decent fuel economy and wondered if being in 6th gear would help, hurt, or if the speed was too low to be in 6th and I would risk bogging down.
Well to answer the 3rd question, in manual mode if you fall below a certain speed in each gear the truck will automatically downshift. I found while in 6th gear in manual mode that the truck would shift in to 5th right around 36MPH which was consistent with the bottom end of 5th in "auto" mode. I suppose that is the point where the RPMs fall below what is acceptable to run in 6th.
So I performed a very short, very unscientific test that I would like to offer up for discussion.
I ran the same exact 2.5 mile length of road 2 times. 70*F, little or no wind. I set the cruise control at 40MPH for about 30 seconds each time prior to resetting the MPG readout.
I reset the MPG readout at the exact same spot both times, going the exact same speed (40MPH) in cruise control. I made sure I was clear of any traffic so I could run about 2.5 miles without any further input.
Test 1 was "auto" mode which stayed in 5th gear all but once when the truck briefly downshifted to 4th while going up the largest hill along the route. At a certain point I recorded the MPG and stopped the test.
Test 2 was manual mode set to 6th gear. The truck stayed in 6th the entire time and had no problem maintaining the 40mph speed. The truck didn't bog or shudder whatsoever going up the hill although I did notice a distinct change in exhaust note.
Below are the results of my short test:
Auto Mode:
Manual Mode 6th gear only:
I realize these were controlled conditions with no traffic, but if you travel on long stretches of road with light traffic frequently in the 40-45 mph range give it a shot! Post here if anyone else wants to conduct something similar.
I found myself cruising along in very light traffic around 40MPH and noticed that I was in 5th gear.
After a little fooling around I found that 5th gear runs from ~36mph to ~49MPH under light throttle while cruising.
I was getting decent fuel economy and wondered if being in 6th gear would help, hurt, or if the speed was too low to be in 6th and I would risk bogging down.
Well to answer the 3rd question, in manual mode if you fall below a certain speed in each gear the truck will automatically downshift. I found while in 6th gear in manual mode that the truck would shift in to 5th right around 36MPH which was consistent with the bottom end of 5th in "auto" mode. I suppose that is the point where the RPMs fall below what is acceptable to run in 6th.
So I performed a very short, very unscientific test that I would like to offer up for discussion.
I ran the same exact 2.5 mile length of road 2 times. 70*F, little or no wind. I set the cruise control at 40MPH for about 30 seconds each time prior to resetting the MPG readout.
I reset the MPG readout at the exact same spot both times, going the exact same speed (40MPH) in cruise control. I made sure I was clear of any traffic so I could run about 2.5 miles without any further input.
Test 1 was "auto" mode which stayed in 5th gear all but once when the truck briefly downshifted to 4th while going up the largest hill along the route. At a certain point I recorded the MPG and stopped the test.
Test 2 was manual mode set to 6th gear. The truck stayed in 6th the entire time and had no problem maintaining the 40mph speed. The truck didn't bog or shudder whatsoever going up the hill although I did notice a distinct change in exhaust note.
Below are the results of my short test:
Auto Mode:
Manual Mode 6th gear only:
I realize these were controlled conditions with no traffic, but if you travel on long stretches of road with light traffic frequently in the 40-45 mph range give it a shot! Post here if anyone else wants to conduct something similar.
