I agree with Cactus. Don't expect to be able to floor it at every opportunity and get 20mpg.

 

The coolant thing throws me for a loop. I have nothing for you other than alot of self testing and trying to figure out where it is going. Probably a slow leak that is only leaking when you are driving when the fluid pressure in increased. Fill up your fluid, take a 200 mile trip and check at the end of the trip if your fluid went down. Also, on the same trip, set your cruise at 65 and check your mpg then. I average 13-14 mpg with mixed driving and I get on my truck all the time. When I go on long roadtrips with freeway driving I get a little over 18 mpg. This is driving a Megacab that is usually loaded with stuff too. And all of this without the MDS (megacab=no MDS). I have seen members on here with qaub and RC that are getting over 20 mpg with a similiar setup as yours. Just take a weekend and do some road testing, see what you fnd, then come back an we will see what we can do. Good Luck..

 

I have a recent post on here complianing about a sudden loss in gas mileage, however I took her into the dealership yesterday, told them the symptoms, running cold, no heat, bad gas mileage, they blamed it on a bad T-Stat, replaced it. I'll have burned a tank through her later today when I leave my job site, but on the way up here, 150 miles, the computer read my normal reading around 19.8 MPG. Mind you that's mostly interstate driving. But I have a 50 series flowmaster on mine, and if I don't kick the o/d off around town I can easily get 14-16, and Highway I've seen 18-21...

And By the Way, everyone GRILLED me when I said I put super in my tank, and no one said anything to this guy about it?!? lol I was told (Repeatedly) that our trucks are optimized for 89 octane, and will get better gas mileage with it than super... You also didn't say anything about what kind of road your mainly driving on... If you're mainly an in town driver, that's probably the best mileage you're going to see. Yeah, your car might be getting better mileage, but that motor isn't having to tote around a 5,500 lb vehicle, not to mention it's about as aerodynamic as a brick on wheels...

 

Dude, you had better focus your attention on the antifreeze leak and attend to the fuel mileage later. I’m not trying to jump to conclusions but my father in-law had a Chevy S10 that was doing the same thing, going through antifreeze. I suspected it was internal but he continued to just more fluid until he finally took it in to a shop. In his case it turned out to be an intake manifold water leak that was allowing the antifreeze to seep into the combustion chamber. Problem was when he would turn the engine off the remaining pressure allowed the antifreeze to go past the piston rings unburned and allowing the water to travel down the connecting rod. Well they replaced the intake manifold gasket and everything was fine for about a month, than the rod bearing went out! Water and oil you know don’t mix very well.
You really have to find out where that antifreeze is going and the sooner the better. It could even explain why the fuel mileage is slightly below standard if it’s getting into one of the cylinders. Not trying to scare you but going through a gallon of water isn’t a small leak.

 

Same here...

 

i've taken it to the shop and they say nothing is wrong with it. everything is fine. they won't fix it, it's been in for it 5 times now and i can't lemon it cause they say there's nothing wrong. i think it's a head gasket or intake gasket but the dealer doesn't want to do anything about it. I don't smeel anything at idle, wot, with the heat on. they've pressure teasted it that turned out fine the 4 times they have done it. i'm about ready to take my plugs out an see if any are shiny. maybe then the dealer will so something

as far as the MDS goes mine still drops cyclinders when you put it in tow/haul. all that does on mine is change the shift points.

it's fustrating cause i love the style of the truck and it does get out of it's own way. but i've had these problems since i bought the truck with 5 miles on it. i'm about ready to go back to a chevy

 

Ask the dealer to explain where the coolant is going if there is nothing wrong with it !!I would go to another dealership maybe you will get better luck from them

 

Take it to another dealer, and file a complaint with Chrysler. The dealership will loose its 5 star rating if they get too many complaints. If you aren't taking it to a 5 star dealership...you should.

I would bet money it is a head gasket...and it is only going to get worse. It is probably only leaking when reaching max temp and it is being burned off as soon as it leaks. It is hard to recreate that in the service bay.

If it fails before the warranty runs out the dealer has to repair it, if it fails just after the warranty expires, it is on you.

 

OH and as far as the gas mileage goes, if you go by the computer i get 14-15 or so aroundtown. but if you do the math, how many gallons to how many miles it comes out to be like 11-13? what's up with that. i guess i just got a dud! maybe i should paint it yellow and call it a lemon

 

With the gas prices on their way up, i would think that you guys with the MDS on your trucks would be happy?