- Nov 1, 2020
- Reaction score
- Central NY, AKA Upstate NY
- Ram Year
- Eco Diesel _3.0
The same thing happens with my EcoDiesel. If I use the cruise control the truck stays at whatever speed its set to... and will shift up and down to vary the more torque and HP to maintain that speed. It will downshift both going up and down hills to hold that speed. I don't think that using the cruise and allowing the shifts hurts anything on the truck. HOWEVER, I have noticed that my MPG will drop a little more in mountainous terrain when using the cruise. I suspect its because of the downshifting on the downhill side of the mountain.So per my other post (will not go into details), I ended up needing a full size truck and gas mileage. I ended up with the V6 3.6 w/ the 8 Speed. It is a 2018 Ram 1500 crew cab with 4x4. Blue sport if that makes any difference. It also has the 3.55 just in case I need to tow the trailer from time to time.
So driving up north for work once a week (and every other Thursday), my trip is about 170-190 miles round trip. It is pretty much all expressway. I know I read reviews about the engine's torque and slight inclines, depending on RPMs/Speed I am running, will downshift to keep speed. I notice it a lot and I'm OK with it.
I find myself driving in a few different ways and curious if any of them will lower the life of my drivetrain (transmission, rear end, converter).
I drive with cruise control on because it takes some stress out of my leg. It spends the time in 8th gear until I hit some inclines that are big enough to start bogging down the engine slightly, forcing it to downshift to 7th. A few hills will bring it down to 6th for a short time to maintain the speed as well. I can tell when it is going to down shift because the real time MPGs hits about 17 and can't keep up the speed (giving more throttle).
I do not have the exact number of times it down shifts, but it is a lot. Much much more then the GMC 2.8L Diesel I had. Though that was a 6 speed and it had close to 400 ft/lbs of torque which was available much lower in the RPM range. Completely understand the difference between the two trucks and I'm ok with it. I would guess the truck could down shift into 7th ... 30 times? Down into 6th maybe 5 times or so.
I do not use cruise control. I can see/tell that I’m approaching a hill. I usually have the realtime MPG displayed on the dash cluster display. So I will try maintaining the speed I want, slowly pressing more on the pedal as I climb the hill. As the MPGs start dropping, at about 18MPG, I will start releasing the pedal some. Basically I’m keeping it in 8th gear by giving it as much pedal as I can before it shifts down to 7th. I will not keep the speed on the hill but it slowly decreases, maybe by 2 or 3 MPH. I basically get back up to speed once I am over the hill. Sometimes I can have it drop 4 or 5 MPH. Just depends on the hill.
This method, I know it isn’t shifting as much but I feel like I’m just working that 8th gear much more. Trying to get every bit of power through 8th without letting it free up some more torque in 7th.
So between one and two… Is one where it shifts more often really going to harm anything? Or is two going to stress anything by me trying my hardest to just keep it in 8th gear? I wish cruise control would do this for me, keep it in 8th… but I’m OK doing it either way.
I may be thinking too much into this. If I have no worries and either way is really fine, then I will try out both and see which ones net me a little better MPG. Right now, three tanks, I’m just over 20MPG on two of them and under 20MPG on one. The one under 20MPG was due to me letting it idle a lot because I was running an ozone machine through to clean the smell inside. Worked great.
Any input would be greatly appreciated! I have a feeling I’m over thinking this though… I always do. I just want to keep it running as well as it can for as long as it can. Thanks all!
Bottom line: I use the cruise control on longer trips when I know my right 60 year old skier knee won't be happy playing with the throttle all day. I always use it in hilly to mountainous terrain when towing because I don't want the truck to over run the speed going down a steep grade. When I tow using the cruise control my truck will hold its set speed on the steepest interstates and US highway truck routes thru the Rockies. I also use the tow/haul button on the dash when towing.