V6 and 8 Speed Transmission (Driving Habits)

[wildneg]

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).

Scenario One
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.

Scenario Two
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!

 

[ramffml]

Where's the fun if you can't over think it?

CC sucks. It has one mission, keep you at a permanent speed. As you've discovered (and its even worse when towing), you have far better control over your truck by cruising down (increasing speed) and coasting up (bleeding speed) hills as needed.

You will definitely notice more shifts, not just v6 gas vs diesel's torque but also 8 gears vs 6, these transmissions are designed to keep you at the optimum RPM and will shift often to put you there. But as long as you don't care about holding your speed to an exact fixed number, you can have much better experience without CC.

Edit: And don't overlook the gear limiter either, on bad hilly sections you can set it to 7th (for example) and save a lot of up/down shifting from 8th, either with or without CC engaged.

 

[PolarisCobra]

I am trying to do the opposite of overthinking this. What is the harm in the transmission shifting a few more times? Seems to me that is what it is designed to do. I would not think it will substantially shorten the life of the system, and we need not worry about it.

Does anyone have any data that says different?

 

[gfh77665]

The question you pose is not really about the truck, its about you. What do you like best? Believe it or not, vehicles are made to serve us, not the other way around.

 

[Yardbird]

I never shift to drive and leave it there. I always select the right gear for the road speed and terrain. Much better performance on rolling hill 35 mph (4th gear) and 40 mph (5th gear) roads. 6th gear for 45 to around 60, then 7th for everything else.

I consider my truck a 7 speed, as with 3.21 rears, 20" tires, and a V-6, 8th gear is useless at any speed unless going downhill.

Didn't want 3.21, but the exact truck I wanted at the price I wanted came up, just had 3.21 gears.

No problem. I always select my gears in anything I drive anyway, and with 3.21s it hasn't changed 2 to 3 gears before 25 mph. I have a V-10 to pull with, so there's that as far as pulling.

I average 19.5 to 20.5 mpg local, and 22 - 23+ on trips.

 

[crash68]

I may be thinking too much into this.

Yeap, your thinking way to much into this. Set the cruise and enjoy the ride, if you listen to old farts who stuck in the past they'll have you believe that all trucks should be carbureted with manual transmissions.
These ZF 8HP transmission are pretty much bullet proof, very few reported problems. There one that was into the 700K mile range that most of those miles were towing trailers across country.

 

[star_deceiver]

The 8HP and 845 are smarter than all of us. They’re never in the wrong gear. They don’t upshift further than they should, nor at inappropriate times. The only time I select a certain gear is when I have a long downhill and I’m trying to hold a slower speed without riding the brakes.

And if this truck could have been optioned with a stick shift, I would have gladly paid extra for it!

 

[HunterCat]

You can also use the Tow/Haul button and this should give a better experience with less shifting on a hilly drive (I think this is suggested in the owners manual). I think you're fine regardless but you can try a couple of methods during your drive while watching the transmission temp gauge to see if there's any actual difference.

 

[Random_Walk]

I have never used CC on the truck since I got it. Ever.

Then again, I drive on some wicked twisty roads with variable inclines/declines, so keeping speed is a tad impossible. I might try using CC the next time I find myself on any serious stretch of I-5 or such... I average around 20-21mpg.

 

[EdGs]

deleted

Sorry, just realized I was in the v6 section, posted about my hemi. Blame it on old age.....lol

 

[Doug Ram]

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).

Scenario One
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.

Scenario Two
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!

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.

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.

 

[Sherman Bird]

Where's the fun if you can't over think it?

CC sucks. It has one mission, keep you at a permanent speed. As you've discovered (and its even worse when towing), you have far better control over your truck by cruising down (increasing speed) and coasting up (bleeding speed) hills as needed.

And Officer "Friendly" knows this. Why do you think they set up speed traps at the top of a hill looking at the down wind descent with their radar!!? Like a turkey shoot! "And the beat goes on! Yadda Da Da Da"!

 

[ramffml]

And Officer "Friendly" knows this. Why do you think they set up speed traps at the top of a hill looking at the down wind descent with their radar!!? Like a turkey shoot! "And the beat goes on! Yadda Da Da Da"!

Yeah they're not likely to pull me over with an average of 65 mph when there are guys whipping by me in the left lane. Here in Canada the limits are 100 km/h but you can safely drive 120 without getting pulled over, that's the speed almost everyone is driving (but I sit closer to 105/110).

 

[Sherman Bird]

Yeah they're not likely to pull me over with an average of 65 mph when there are guys whipping by me in the left lane.

Said my brother-in-law.... when a cop pulled him over and wrote HIM up for 65 in a 55 zone while everyone ELSE whizzed along at 75 plus.. Brother in law said cop told him that if he (Bro in law) had been keeping pace with those dozen or so cars, Cop wouldn't have pulled him over necessarily due to law of average. Methinks the cop was a rectile orifice.

 

[ramffml]

Said my brother-in-law.... when a cop pulled him over and wrote HIM up for 65 in a 55 zone while everyone ELSE whizzed along at 75 plus.. Brother in law said cop told him that if he (Bro in law) had been keeping pace with those dozen or so cars, Cop wouldn't have pulled him over necessarily due to law of average. Methinks the cop was a rectile orifice.

This is a silly argument. Cruising and coasting up and down hills doesn't mean you're more at risk from speeding tickets than using CC. Obviously if that worries you then adjust your max speed down regardless of which method you're using.

 

[Sherman Bird]

This is a silly argument. Cruising and coasting up and down hills doesn't mean you're more at risk from speeding tickets than using CC. Obviously if that worries you then adjust your max speed down regardless of which method you're using.

Not silly at all. When the national speed limit was 55, I observed how Cops would catch speeders from the top of a high spot pointing their radar guns at the top of the last rise.

I'm no genius, but on many cross country trips, I would speed and slow up JUST before I crested a rise in a road. Often I'd see a cop up on the next rise with his/her radar gun catching speeders. If there was no cop, I'd speed on the downhill side and up to just before the next rise if the coast was clear. I never got stopped. Nowadays, speed limits are high enough that my old tactic is out dated.

 

[ramffml]

Not silly at all. When the national speed limit was 55, I observed how Cops would catch speeders from the top of a high spot pointing their radar guns at the top of the last rise.

I'm no genius, but on many cross country trips, I would speed and slow up JUST before I crested a rise in a road. Often I'd see a cop up on the next rise with his/her radar gun catching speeders. If there was no cop, I'd speed on the downhill side and up to just before the next rise if the coast was clear. I never got stopped. Nowadays, speed limits are high enough that my old tactic is out dated.

If you drive as described (and as I've described), you bleed off speed as you head up larger hills. That means you could very well be at/below the speed limit by the time your nose is peaking over the hill.

The technique works perfectly. Obviously if your speed is too high in any given section of road you may be flagged down. So drop your speed. That's all beside the point, which is, CC sucks and it's better to coast down and up hills, doubly so when towing.

 

[1979PowerWagon360]

Wildneg, I also think you're fine using the cruise control if that's your preference for ease of driving this trip once a week, and as said these are sturdy transmissions and I don't believe you are going to bother the rear end either. At most, if it'd give you some peace of mind you could install a larger transmission cooler than stock but I think you're just fine.

 

[stormcom]

If you read anything, the v6 is a high rpm engine. It is just keeping in the power band for the truck. I have had all 3 (v6, hemi and eco). The computer drives the truck. I thought the same thing but saw several videos about the power band in the 2500rpm and up to 6500. You will be just fine. Set the button and enjoy.

 

[StickyLifter]

The clutches and brakes inside of modern transmissions use much more advanced friction material that is capable of a lot more cycles than older materials. The valve body and pressures are designed to close fast while still allowing some slip but alleviating wear from shifting. Also modern transmissions don't have bands, which caused the majority of wear issues in older designs.