I have reached 10k on my 05 and have not noticed an increase in mpg. For that matter I have had 5 trucks and 4 tractors in my life and have never noticed an increase in mpg with an increase in mileage.
Is this just a myth?

If you have had an increase in mpg, at what mileage did you notice it? What type of increase are we talking about? 1/2 mpg? 1 mpg?

Thanks

 

My 03 steadily increased until about 60,000 miles... When new I averaged 15 mpg; At 40,000 miles it had increased to 16 mpg and at 60,000 miles it was about 17 mpg. Although I believe there are a lot of variables/contributing factors, towing/hauling, driving habits etc. I also used synthetic oil and fuel additive which seemed to help

 

My 06 only has 5900 miles on it, but on my 02, I noticed a jump in mileage at ~8K, 17K and 28K miles

 

I've noticed jumps at 5k, 10k and 20k. I've also heard of rumored increses at 40 and 100k. I just calculated fuel consumption/hr on my spread sheet and the greatest difference in consumption occurred at 5K or about 150hours in my case

 

My 04 started out at 15.5 and at 60,000 miles it still gets 15.5.

 

On both my trucks, '04 and '06 I experinced a decrease in MPG after the first oil change, 1 to 2 MPG. The '04 at 50k miles was still getting the same since the first oil change. The '06 with 9k miles has not improved since the first oil change but I have never used an entire tank without pulling a load of something so I get anywhere from 9.8 to 17.4...350 cc 4x4 4.10 drw

 

I think its new vehicles in general now, manufactured with tighter tolerances. My dad's last 2 GMC gassers got better after 10K as well