Engine/Transmission (1998.5 - 2002) Whats up with my fuel Mileage?

[jrandol]

I must say I am a little bewildered here.



Bought my truck new about 3 months ago with 13 miles on her. Truck has been babied thru to now where it has a little over 10k on her. Changed fluid regularly and just changed a fuel filter along with air filter the other day. I get fuel at the same station weekly which is a very high volume truck stop and my mileage is worse know than it was 5k miles ago. Only mod I have made to my truck is straightpiped about 3 weeks ago. Since then my mileage is down to about 17 highway. Before I was consistently getting 19-20. Could my straight pipe have something to do with this or is it just #2 diesel?

 

[Whitmore]

Actually the #2 diesel is best for economy, it has higher centane content than #1 does. #1 has a lower pour or cloud point, You are prolly getting a winter blend of 50/50, this will drop your mpg about 2. dont worry be happy sounds like you have normal mpg, you will get 20-21 this summer



cheers, Kevin

 

[RonaldLarson]

Good advice

But remember, Cummins engines don't like to be "babied". Beg, borrow or steal a big heavy load and run it up and down some serious hills. It still takes 20-30 thousand miles before they are broken in and begin to give their best mileage. Interesting fact; initial mileage is normal, then it drops off till breakin begins, and goes back up. I use #2 fuel all year with no problems, using Power Service DFA to prevent fuel gel. Around here, only Exxon has straight number two all year. It definitely helps mileage and performance.

Ron

 

[klenger]

Winter blend fuel is my guess. It makes quite a difference. I've noticed less power when towing on winter blend too.