New to the diesel pickup scene. Used to turn wrenches on USMC amphibious assault tracked vehicles w/ 903 turbo charged Cummins when in the Corps back in the early 90s (including Desert Storm), so not completly inept.

I just got a new-to-me 2006 SLT 2500 Quad cab 4x4 w/5.9 Cummins and AT. Picked it up with 73,500 miles last month. Seems to be factory STOCK, ie; no MODS.

The truck will be used as a daily driver 5 to 15 miles to work depending which job location I work at. Sometimes at work (3-4 times a month), it may idle most of the day or night for temperature controlled comfort for me. Also bought it to tow a 27' Toyhauler 5-6 times a year, maybe more, now that I have a truck that can pull it safely! About 400 mile round trips so far. My old '04 GMC 1500 Z-71 towed it, but was over it's capacity of 7,800 lbs - trailer coming in at 9,400 lbs. I can load trailer to it's max of 11,600 and still be under the Dodges max of 13,000 lbs for towing.

I took it to Sturgis S.D. bike week from NE Florida towing an enclosed bike trailer. Truck alone weighs in at 7100 lbs at the truck scales at work. On the way, we weighed at a CAT scale and came in at 12,500 lbs. That makes 5,400 lbs of trailer, 2 bikes, 4 people, and gear. I know weight co$t$ to move, and wind resistance adds $ to the co$t$.

I averaged 12.2 mpg the trip. 13.5 and 13.6 for a few tanks was the highest when I was able to get the other truck to slow down to 70ish. Running 80 mph dropped mileage to 10 and 10.2 mpg.

The other truck was a Dirty-Max 2500 w/ BullyDog programmer. It was consistantly blowing big black clouds on any grade we came to. But he constantly got better MPG than I did, hitting 15.3 mpg 1 or 2 times, but trip average for him came in at 12.85 mpg. His rig weighed in at 13,400 but he towed an open car trailer with 3 bikes on it (less wind resistance) and had a topper to keep wind off the trailer front. Bikes got sooted up pretty good, especially the front right one.

My selling dealer did complete fluids change before I bought it (oil, both axles, AT, and transfer case) and I did oil change and fuel filter change with 76,000 miles before leaving on the trip, as oil change during a 4,000 mile trip isn't desirable. After the trip I'm at 80,000 miles.

I am extremely pleased with the performance of my Dodge, but felt mileage should have been slightly better. I am not interested in changing everything under the truck, I am NOT wanting to tractor pull or drag race, but only to improve economy and maintain a reliable truck. I know from my bikes that fuel management from the factory is generalized programming for the masses and a fuel programmer can tune better performance and economy on them, SO, I am assuming a diesel programmer will help. From what I have read, the Smarty or Smarty jr may be what I am looking for. IF something happens to the truck, I have read the Smarty programmers are undectable when removed before taking back to dealer. Other programming recommendations? Why? Do I need to add any gauges and why? What will I be looking for? Ranges to keep within? Why?

Like I said, not interested in altering everything, but give me valid reasons to add or change any factory system. Cold air intake seems like an option I'd like to try. I tried to look up the Home Depot cold air mod and not able to find out what to do, so I don't know if it is something I want to do. Also, from my bike forums, I know minor mods can make big differences in performance/economy. MAJOR mods make major gains in performance, but I know they also promote heavy throttle usage - defeating any gains in economy. One bike has programming with minor intake mod, and gets better than stock power and economy, the other has MAJOR mods (intake, exhaust, compression, and fuel management), and does get better mileage, but hardly ever does because of the grin factor when twisting the throttle! I would like to refrain from this effect on my Dodge. LOL!

I also would like advice on how often to change the oil and filter. I have read to change the fuel filter every other oil change. Is this good advice?

Also, A/C is not as cold on passenger side as on the driver side. Takes a few seconds to change to defroster and to other positions. Is this normal?

 

Your mileage was about right towing for an 06'. 69mph is the sweet spot for towing and fuel mileage. Speed up and you loose mileage. Sounds like your A/C is low on R134a. Common symptom. I would put analog gauges on the truck. Boost, fuel pressure, and EGT. You will learn what is the norm after driving it with them in. The Smarty Jr. will be your best beat for fuel mileage as long as you keep it on a lower setting. The higher settings won't do well for your tranny while towing. I would also get a brake controller for the additional brakes on the toyhauler while towing. Maxbrake is what I would suggest for best results. It's a safety thing.

 

Thanks Spooler. I do have electronic brakes and a controller for the Toyhauler. I wouldn't have been able to tow it without them with the GMC 1500.

 

Ah, I was reading your signature.

 

LOL! Yea, that was when I bought it. It had not had a brake controller installed then. My installer for my brake controller said the wires were still tucked up from the factory and had the dust on them that they had not been used so far. No goose neck or 5th wheel hitch has been instslled either. I'm guessing maybe, a medium sized boat may have been the heaviest it has towed so far. My trailer will be the heaviest, by my guess, that will have been behind it when I take it out in 2 weeks.

 

Speed is the killer. The truck is about as aerodynamic as your house. At 80 I get 18mpg. At 65 I get 21-22mpg.

You can do a lot of mods that will gain a little mileage here and there. But a lot of them are expensive, and will take forever to pay off.

Some things people do actually make the truck work harder, and cost fuel mileage. Like big off road tires. If you don't need those, stick with "skinny" highway tread tires that offer good traction and low rolling resistance.

I use a Smarty Jr, set for economy and I actually turn the power down a bit, to about 85. It saves a little fuel. And - I'm hoping - less power than I need will take some strain off the rest of the drive train.

Do good maintenance, drive reasonably, and remember that it's a 3.5 ton brick. With gobs of torque. And air conditioning.

Oh, and I'v noticed that if the air filter gets dirty, the mileage really drops. Change it when the indicator gets near the bottom of the green zone.

 

I took it to Sturgis S.D. bike week from NE Florida towing an enclosed bike trailer. Truck alone weighs in at 7100 lbs at the truck scales at work. On the way, we weighed at a CAT scale and came in at 12,500 lbs. That makes 5,400 lbs of trailer, 2 bikes, 4 people, and gear. I know weight co$t$ to move, and wind resistance adds $ to the co$t$.

I averaged 12.2 mpg the trip. 13.5 and 13.6 for a few tanks was the highest when I was able to get the other truck to slow down to 70ish. Running 80 mph dropped mileage to 10 and 10.2 mpg.

...and you think that's bad?
Holy crapola... I'm ticked off if my mileage drops below 20 on the highway pulling a ski boat at the speed limit or about 60 at the most!
Hooked up to our 40' 3-axle enclosed fifth wheel car trailer I can average 17 on the flats between northern and southern california...and I'm happy with that.
Speed is definately your enemy, the best thing and cheapest thing you could do is drive slower.. plain and simple. It's a lot eaier on your tires as well as the engine coolant, transmission and other stressed components. just sayin'

 

your truck has in- cylinder egr you can get rid of most of it and gain about 40% increase in mpg. efi live was not available when we did our fleet and we had to change nozzles to 50 hp to shorten fueling duration. for you the best thing is to change cam to a pdr or colt stage II and get efi live tune from anarchy. once you do this mod, the oil will stay cleaner, you can increase drain interval to 10,000 miles. use dello 15w-40 and fleetguard lf16035 filter. the fuel filter is not good enough. you need to add a 2 micron filter. pm me for instructions.

 

Most bang for the buck is efi live economy tune drop in afe progaurd air filter.Do not go with a cold air intake its a big watse of money.same with a big intake horn you dont want to spend $225 just to get it to spool slower.A bigger turbo will help with a extra one to two mpg.