2 MPG Drop??

[DCornelius]

I recently filled up at the same gas station I always do. My hand calculated mpg was 13. 6. It is consistently between 15 - 15. 5 mpg for city driving. No change in driving habits or any towing or hauling. Any idea what could cause this? The truck has 17,500 miles on it and I just changed the oil and fuel filter at 15,000.



The only thing I noticed was a sticker on the gas station's fuel pump that indicated they were using low-sulphur #2 diesel, and that 2007 model diesels should not use that fuel. That sticker was new. Could a switch in diesel be the culprit?



Thanks for any help

 

[GDamitz]

I get worse mileage when I use the Arco Ultralow sulphur diesel. 1-2 mpg lower.

 

[MFalkinham]

Could be due to carbon build-up on the injectors. I'd go and buy a 2 cans of SeaFoam. Drain the fuel filter canister and dump one can directly in there. Dump the other can into the fuel tank. Start it up and run it for a few seconds, then shut it down and let it sit overnight to soak. After that, drive it hard to get the combustion temps up and burn off any deposits.

http://www.seafoamsales.com/motorTuneUpTechDiesel.htm