Those of you with around 10k or more miles on your 600s, Did you see any mileage increasements with your added break in?

 

I only have a little over 7000 miles but I'd still like to answer. I did see a lot of increase over this period of time. The truck started out at about 18 mpg highway and after all these miles, a couple thousand of them towing a TT, it's up to about 22 highway! I havn't gotten the latest TSB yet either, but I'm planning on getting it soon.

 

Took delivery in late May. I now have 17k + miles and the new flash. I'm now getting about the same mileage loaded and unloaded. neither good.

 

I have a little over 14,000 and have not seen a noticeable increase for many miles. Milege is better than when I had 4-5000 miles but still not good around town.
I drive the truck easy, and pull a 5000# trailer around town most of the time and average about 11 mpg.
Recently I did drive about 100 miles on hwy., no trailer and was getting about 19 mpg. at 70 mph.
I purchased in early March.
Have had no flashes done yet.

 

awesome keep them comming

 

Well I do not have 10 k on mine but I will chime in anyway. Have pulled an 8000 lbs trailer around 1500 miles. Truck has 6800 miles on it now. When truck was brand new mileage was around 17.0 highway. Currently if I drive 65 mph during my 50 mile commute I can get it up to around 20.0 mpg. Pulling the 8000 lbs trailer at 65 mph I get around 12.5 mpg. So I do think the breakin theory is valid. Truck does seem to be getting better mileage. I would say a person can except around a 2 to 3 mpg improvement after break in. I do believe that driving style has a huge impact on mpg in these vehicles. Remember that ol' physics formula Force = Mass * Acceleration? The more you accelerate the more force must be produced. Of course if your mass is large then it is a double whammy! These trucks are producing gobs of power. So much power that they make you feel like you are driving a 3800 lbs car instead of a 7000 - 8000 lbs work truck. I find it amazing that the trucks we are driving weigh double what a typical family sedan weighs! So that takes significant amounts of go juice to push 'em around. I try as much as possible to be easy on the throttle. I have more time than money for diesel fuel!

 

25k miles
68 mph - 2000 rpm 18 to 20 mpg, depending on head-wind
70 + mph 16 to 17 mpg
3500 lb gooseneck livestock trailer w/ 6500 lbs of cows (in hills West of Houston) 11 to 12 mpg

 

Mine has not changed enough to tell. I have around 11,700 miles on now and it has always been at around 15-16 local and 17-18 at 65mph hyway.

 

Here's a graph of my mileage. Per tank (not filled 100% each time), averaged over three tanks, and total average...

It's hard to see a trend, so much of the MPG depends on how the truck is used. Around town? Long trip? Towing?