I have a 04 RCSB chevy truck everything is stock and im getting around 10-12 mpg anybody have any ideas why it is so low?

 

5.3? Might be your right foot. Driving habits have a lot to do w/ mpg. Also, excessive idling or sittin in traffic. I've never heard of anyone getting that bad unless it's a 6L &/ or 4wd.
More details. What's the rear end? Is it 4wd?
How's the state of tune? Something is missing here. Really low tire pressure, & so on, & so on. Towing?
Too vague.

 

its a 5.3 4wd 3.73 gears.. normal drivng most of the time i get on it once and a while.. and tire pressures are okay

 

Stock rims and tires?

 

Its faster to just look at another thread that has already mentioned pretty much everything it could be.
Obvious differences, but all the same stuff causes bad MPG.
https://www.performancetrucks.net/fo...d.php?t=430715

 

yeah it has stock wheels and tires and it mostly city driving not alot of traffic either

 

Somethings wrong, my 05 bone stock would do 15 at worst and i have a heavy foot.
Maybe take it in and see if you have any codes?
How is the maintenance on it, good oil, clean filter, have you ever done fuel treatments?

 

ive had amsoil in it for about 3000 miles and no i havnt done any fuel treatments

 

depending on mileage, check plugs, filter, and like Jeff said maybe run a bottle of sea foam thru the tank and see.

 

its only got 36000 miles on it but i guess ill try some fuel treatments