Nbs 6l 6spd Questions

HeavyFuel · August 5, 2007

Hey Guys,

Probably not that many of these out there owned by guys on the forum since most guys tend to go for the diesel, but for those that do -

1. have you had any issues yet?

2. What does the gas mileage look like? I would be most interested in an extended cab long bed 4x4.

Thanks in advance.

LuvMyZ71 · August 6, 2007

Hey Guys,

Probably not that many of these out there owned by guys on the forum since most guys tend to go for the diesel, but for those that do -

1. have you had any issues yet?

2. What does the gas mileage look like? I would be most interested in an extended cab long bed 4x4.

Thanks in advance.

No problems so far, I've got 4800 miles on mine and I tow a heavy 5th wheel, sometimes my 2nd to 3rd shift seems a little hard, but not bad.

In town I get about 10-13 depending on how I drive, towing I get about 6-8 and on the highway I get about 14-16. I also have 4.10s, so if you went with the 3.73 it should be better.

cajunjimbo · August 6, 2007

Hey Guys,

Probably not that many of these out there owned by guys on the forum since most guys tend to go for the diesel, but for those that do -

1. have you had any issues yet?

2. What does the gas mileage look like? I would be most interested in an extended cab long bed 4x4.

Thanks in advance.

no issues yet...i have the '07nbs 2500 crew cab reg bed 4wd and see about 11-12mpg non towing, 6-7mpg towing 7000lb boat/trailer...

SS Crew · August 6, 2007

I've got a 2007 GMC 2500HD with the 6.0. This engine would be a monster if the electronics would just let it go.

The trans takes some getting used to, when it's in 6th any little adjustment of the throttle will send it into kickdown mode. When I do get on it to pass someone, it takes a second or two to send any power out then it downshifts, then it goes. I'm going to get a custom tune to try to eliminate most of the nannying. I'm just kind of disappointed that it doesn't run strong as it should out of the box.

My mileage pretty much sucks like everyone elses: 9-11 mpg city and 10-13 highway. I did see 14.1 mpg come up once on the DIC, but it quickly went back to the 13's at the first grade.

So far no problems other than the trans being overfilled by the factory.

Daubs · August 7, 2007

My mileage pretty much sucks like everyone elses: 9-11 mpg city and 10-13 highway. I did see 14.1 mpg come up once on the DIC, but it quickly went back to the 13's at the first grade.

Man, that's a bummer to see. My 8.1L Crew Cab 4x4 is knocking down 10-11 city and 11-13 highway MPG with the Allison 5 speed tranny and 3.73 gears / 285's. Was hoping to see better MPG numbers from the 6 speed auto tranny.

71chev · August 9, 2007

This past week we made a 6hr run to east central Il. 2007 2500hd, 4x4 reg cab 6.0 with 6sp tranny, 3.73 gear. We ran pretty hard on interstate and got 15mpg. Comming back on county roads and 2 lane state hwys towing a heavy drive over hopper, we got 14mpg. I liked the tranny and the way you can control the shift .

2017HD · August 10, 2007

I have the 6.0L 6sp and 4.1 gears. It is my daily driver and weekend trailer hauler - a 5600 lb Arctic Fox. I ordered the truck for towing conditions here in the PNW which include lots of two lane roads and a mountain range between me and most of my camping spots. Solo the rig averages between 13 and 14 with a combination of hy and city driving. I have not figured out exactly how the DIC computes ave MPG. I usually reset both the gallons used and trip meter with every fuel stop. I have even tried reseting the ave MPG - but it keeps coming back to 13. 5 or 6. Towing I get around 10 or 11 depending on conditions - mostly wind. However I just put on a canopy (a new Leer 100 XL which looks great) which I hope decreases my aero drag and increases my towing MPG. I have not been camping since I got the canopy to see if it makes a difference or not.

The throttle takes some getting used to - along with the adaptive shift on the transmission. When you romp on it there is a delay before the tranny downshifts and the engine gets it on - once it hooks up - look out. I find it better to push the gas about half way down as the engine seems to respond better. It also depends on what gear you are in - trying to put too much into it on a standing start seems to just wind the engine and not produce much go. I have found that keeping the tach at or below 2000 revs produces the best standing starts - and once into 6th ends up at 60MPH. Once it gets into 4 and above you can up the revs and get some real scoot. Climbing hills with the TT in tow I typically put in in 4 and drive by the tach - keeping the revs between 3 and 4000. This also keeps the speed to 50-60MPH.

I have just over 6000 miles and have noticed that when starting out in the morning, the first 2-3 shift is often rough. Once the transmission gets to temp - or even on the second set of shifts it smooths out.

I am just watching the situation for now - but if it gets worse - it is going to the shop.