2008 Chevy Silverado 6.6L Duramax fuel problem

20

Asked by Jan 21, 2014 at 06:49 PM about the 2008 Chevrolet Silverado 2500HD LT1 Crew Cab 4WD

Question type: General

I am only getting 10-12 mpg in my 2008 Chevy Silverado Duramax when other folks
claim their getting 16-17+.  What could be wrong? I had a certified tech put the monitor
on it and it checked out with no red flags or bad codes.

10 Answers

19,415

Do you have the factory size tires on it? Add a quart of transmission fluid to the fuel tank to clean the injectors. Air filter new?

2 of 2 people found this helpful.
20

My driver door says it should have 16 inch tires, but it has 265/17's on it and I'm pretty sure it came with the 17's on it. It's funny you mentioned the air filter. I had the tech check the truck out last night, and through conversation, we pulled the air filter out and it was grey and you couldn't hardly see light through it. I bought a brand new one today, but haven't had enough time to see if it helped.

1 of 1 people found this helpful.
19,415

That is a big part of it. You can also buy a chip for it and set it in safe tow mode and it will increase the mileage and power. Usually 3-7mpg gain. I run superchip in mine.

2 of 2 people found this helpful.
20

Also, are you referring to Dexron III transmission fluid? I have heard of adding transmission fluid to the fuel tank, but wasn't sure it would hurt the engine

1 of 1 people found this helpful.
20

I pull a 33ft fifth wheel camper with my truck or I will be. I just purchased the truck and figured I would be getting a lot better gas mileage. I have not pulled the camper yet to see what mileage I get with it behind the truck. I sure hope the air filter helps

19,415

Yes that is fine. One quart to a full tank of fuel is good for it occasionally.

3 of 3 people found this helpful.
20

Ok.....I'll try it and see if it helps. I appreciate your help!!

19,415

no problem.

tans fluid in the fuel tank is not recommended. Have replace many injectors on duramax's for people using "old school" tricks.

Marvel mystery oil works wonders in fuel gas are diesel it cleans your system out an saves on gas one quart per tank don't matter how many gallons

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