I would first go to basics to get some consistant information. 1) Have you checked your odometer against the mile markers. traveling at least 40 miles on the highway against what the odometer shows, bigger tires turn slower, show less miles and indicate your speed as slower. It appears that you were using the overhead. I would hand calculate your mileage with corrected miles traveled. If you already did the above, MPG is low compaired to mine. Blowing the soot out occasionally and towing something really helped mine.

 

Aw yes, I was once in your position. Then I bought a smarty and I'm seeing 17MPG+ again. I was as frustrated as you are. I had an 02 cummins that got 20 MPG consistantly at 70 MPH then I bought an 05 thinking I was upgrading. I did upgrade with everything but the fuel milage. I saw no more than 15 MPG with a light foot. After much thought and research I found the culprit. Cummins has a third injection event that squirts a little fuel during the exhaust stage which is carried to the CAT to help burn the nasty stuff that the greenies don't like. Milage has sucked every since then. Smarty changes some timing and I think it also eliminates that 3rd injection event. I could be wrong though. I'm getting much better milage now with whatever smarty did to the truck. Still not as good as my 02 though.

 

the smarty cant stop the 3rd injection event

brett

 

I might try a smarty!

 

Tires made no difference. This is all hand calculated! Im not quite sure what Im trying to get at, all of my previous trucks did did very well. Apples to apples they have all been modded never driven with a light foot. I have read alot of post on here about people complaining about fuel economy in the 06-07 and Im tired of dodge saying its normal. Fortunatly it doesnt get any worse towing my boat.

 

What additive does everyone reccomend using, Im leaving tommorrow for NC.

 

I've been putting 16oz of TCW-3 2 stroke oil and 4oz of Power Service Diesel Kleen in each fill for about 5 fills now. My truck SEEMS quieter, and I'm consistently seeing odo reading and MTE adding up to 700+

Of course I have 2WD with stock size tires and RARELY exceed 1900 rpm on the highway. This means NEVER over 70 and more often 65.

edit: Question! Does my '03 have a cat? Or is it just muffler and resonator?

 

I really like the ATF in the tank, works really well. Tried standadyne, and power service, doesn't work near as well, even double dosed it. I'm gonna try 2 stroke oil, I bought a gallon the other day.

 

ATF is not good!

 

the tolerances in a HPCR are very tight. tranny fluid, while it was ok for use in the older diesels...along time ago, isnt safe to use now. tranny fluid has addicitives that are harmful to the motor.

my grandpa used to preach about the use of tranny fluid in his 2 6.5 td's and it never hurt them, but look at the technology differences between the two motors.

there are products out that are specifically designed for our motors and that will be what i use...the 2-stroke....eh ill run that everyonce in a while!

just my opinion...not gospel!

brett

 

What is the build date on your 06 if it is early get the computer flashed with the update for long crank oand white smoke worked for me and my buddy but both of us are running g 56s

 

Where do you find the buid date and what date ?

 

on the little info sticker on the drivers door

brett

 

Get some howe's meaner cleaner & hook up to something heavy & pull it around for a couple hundred miles. Then run the tank dry & add 32 oz. of 2 stroke oil. Dont run 2 stroke with cleaners. The solvents in the cleaners will break down the 2 stroke oil & you will not see any benefits. BTW run the tc-w3 oil. It's ashless & the nonsynthetic is best I'm told.

 

Most on here have always said work the engine and get some miles on it. I have recenlty decided that is very true. For the last few months I have consitantly gotten better mileage 17-18.5 mpg and have not been running any additives. The reason for no additives was white smoke at startup with the MMO/PS mix. Stopped 6 months ago and not more white smoke and same mpg with ot withou wither of the two or both. Two weeks ago i decide to use the TCW-3 2 stroke oil. First tank was very thin Mix of 8 oz. with 19 mpg on a 570 mile trip. This tank I upped it to 32 oz of 2 stroke. I am at 1/2 tank now with 355 mile on the odo. So i should get close to 20.5 or 21 mpg. This is daily driving with about 60/40 highway.

So in short keep driving it, work it and you might want to try some 2 stroke.