How long will it take to reach MAX??

[roperteacher]

This is a MPG question. Just how many "Break in miles" will it take to reach the most MPG you will see from an engine/truck? Mine has been increasing very quickly when new. I am now seeing 22-23 hand calculated empty open freeway unloaded, 19 around town, and 15 pulling 7500#. I have 8200 miles on the truck... when will I reach my "Max" ???? When does the engine officially "Break in"?? My oil has been staying very very clean in the past 3,000 miles. It was very dark the first couple oil changes. . THanks!

 

[klenger]

My 01. 5 seemed pretty well broken in by 10K, but I still felt some improvement up to about 30K. More "seat of the pants" than actual milage after 10K.

 

[jarmar]

Originally posted by roperteacher

I am now seeing 22-23 hand calculated empty open freeway unloaded, 19 around town,...

Wow! Sure wish I knew your secret. I have 11,000 on now and only get a little over 15 MPG, unloaded at freeway speeds.



jr

 

[SRadke]

Mine has been holding a 19-20 overall average for the last 10k. I'm at 25K right now. I don't expect it to get any better.



-Scott

 

[roperteacher]

Mine is NOT a 4x4... thats probably why I am seeing higher numbers on MPG. . My "Pulling" MPG's seems to have dropped since new. Not sure why. . puling is down a bit but unloaded has gone way up!

 

[PJ]

My best was 21mpg and that was @ 55 mph. I avg 19 @ 65-70 mph (unloaded) More would be good. Mine is also a 4x4. Im happy with the 19 mpg figure! Beats the heck out of a gasser. My worst tank was 15. 5 but I really had my foot in it.

 

[Bertram65]

Roperteacher, you have posted a lot of mileage threads, each one with different results. Seems like you are getting really good mileage, although some of your earlier mileage posts were better. As far as break in goes I would be surprised if it changed much after 5K miles.

 

[roperteacher]

Bertram65, the only mileage that has changed on my truck is the PULLING mileage!! My unloaded has really come up. I got 19 MPG and a little over 19 on 2 tanks PULLING..... then it dropped to like 15 or so. Not sure why... . any ideas???

 

[mattymac]

Originally posted by roperteacher

Bertram65, the only mileage that has changed on my truck is the PULLING mileage!! My unloaded has really come up. I got 19 MPG and a little over 19 on 2 tanks PULLING..... then it dropped to like 15 or so. Not sure why... . any ideas???

Might be unconsistant fillups. After 1st click I can get about 5-7 gallons into the tank but bubbly diesel who knows how consistant your fillups can be. I think 10k is about what most people would say here is "broken in" but pulling and driving hard should accelerate this.

 

[DocDetonancour]

Had a friend ask today why his 03 48RE has dropped from 19 to 15 mpg. I asked about the air filter, but he changed it to no avail. He's thinking of adjusting his valves. Does anyone know if that would help or whey he would lose 4 mpg after 22k miles. Thanks doc

 

[klenger]

Fuel filter or maybe it' broken.

 

[ttreibel]

Broken at 10K if you tow, If you run empty all the time can take as long as 30K... ... ... I say tow or not she won't really open up till after 100K

 

[t6_man]

My mileage has fallen as well. Last summer, on a 3600 mile trip (700 miles on truck at beginning of trip) pulling my 5vr, I averaged 10. 8 (hand calc). This year, pulling the same 5vr (with 5400 miles on truck at beginning of trip), I averaged 9. 5 (hand calc) on a 1700 mile trip.



I was expecting my mileage to go UP, not DOWN!!!:{



The only differences on my truck from last year to this year is I had the dealer change the oil and filter, and I changed the rear-end fluid (used Mobil1 75W90 synthetic)