here are the specs
2005 Kenworth
Model T800
Sleeper Size 72"
Sleeper Aerocab Aerodyne Sleeper
Engine Specs Caterpillar
Engine Type C15
Horsepower 475
Transmission 10 Spd
Suspension AG 400
Ratio 3.36
Tires 22.5
Wheelbase 230"

I have noticed a air leak between the turbos.
I usually drive around 70 on the interstaes,but lately I have dropped down to 60-65 and mpg improved to about 5.45 from 5.1
I am going to try the progressive shifting and see if i can get the air leak fixed.

I tried to edit my post,but took too long and I had to rep[ost
thanks for the input so far


here are the specs
2005 Ken worth
Model T800
Sleeper Size 72"
Sleeper Aerocab Aerodyne Sleeper
Engine Specs Caterpillar
Engine Type C15
Horsepower 475
Transmission 10 Spd
Suspension AG 400
Ratio 3.36
Tires 22.5
Wheelbase 230"

I have noticed a air leak between the turbos.
I usually drive around 70 on the interstates,but lately I have dropped down to 60-65 and mpg improved to about 5.45 from 5.1
I am going to try the progressive shifting and see if i can get the air leak fixed.I used to run my cruise control at 70 mph down I-95 a lot.

2005 KENWORTH T800 Conventional Truck w/ Sleeper For Sale At TruckPaper.com

that is a link to a truck almost identical to mine.

I usually run from NC to Ga,Fla,Southern Pa and Ohio,and all points in between.
Most of my loads run between 40,000-45,000
and every now and then I haul 3000 -8000 loads when I can get the loads.

It sounds like you have one of the new engines. Some of those have had some problems, especially with fuel mileage. The air leak might be causing you some problems. I would check my driving to see that you can plan stops and starts and not get into a big hurry when doing either. One thing you might do is find a dealer who can check your ECM. There could be something that is not working properly that is causing the problem. It is usually not expensive for someone to check the ECM.

What do you know about it? Please, tell....

Tommy, CAT is VERY specific engine, and assuming there is nothing wrong mechanically, the way you drive it, makes all the difference. It's not just a speed, it's also how you get to it. Be very gentle, try to keep your RPM at around 1300, and not over 1500 ever, unless you are going down the hill. Let him do the job, don't push it, unless you absolutely have to...you might be surprised. Your specs is about perfect, so check all the other stuff, and you'll do fine!

Usually, this is a symptom of a leaking Charge Air Cooler. The higher speeds are compensating for the leak, when you slow down you loose pressure and your fuel mileage starts to drop.

I'm sorry to say, but with a 05 C-15 ACERT, thats about the best your gonna do man. I did everything I could to my 05, and I still was stuck around 5.5-6.2mpg

Wrongway Tommy,

I drove the same truck with Tmc although it was 13 speed, same Cat engine with 3:36 rears and I averaged about 6.2 mpg. I didnt always progressive shift like I should have and I was pretty much at the limit (75-80k) most of the time. I'm sure I could have gotten much better if I cut my idle time down too. just my .02

a update fellas!
I have tryed to do a few things different
like some progressive shifting and also slowed down
I would set the cruise control at 1200 rpm`s [ 58 mph ] and just sit back and cruise
and it was kinda hard slowing down and being the slowest truck on the road
this week I`ll set it on maybe 1300 rpm`s and see how that works

my mpg increased a lot so far
here are some figures I got and figured them when I filled up- a lot better than 5.1-5.3
6.43
5.33
6.523
6.23
5.65
6.67
6.523
5.29
5.88
I looked for light loads and sometimes I got heavy loads but the worst
mileages was with heavy loads up some long runs thru the hills

I am going to have a mechanic look at my truck soon as I am go9ing on a short vacation with my wife later this week

thanks guys for the imput!

Tommy aka skidrow