Angler2184

Hello, I own a 08 Silverado 1500 V8 4wd with 33,000 miles. My gas mileage used to be 16 city 18-20hwy until the last couple weeks. Now it is 12 city 15hwy. I recently changed the air filter and checked the tires and still getting the same mileage. I am not sure what else to look at...Thanks

tsduke

How long have you been getting the lower results? What part of the country you in?

JK23112

I hate to say it, but could your gasoline be to blame? In some parts of the country, the EPA requires gasoline to contain 10 percent ethanol (E10). Ethanol has a lower BTU content and thus contains less "energy" than does straight gasoline.

E10 will cost at least 1 to 2 miles per gallon because of this.

P.S. On a negative note, there are people in high places who seek to INCREASE the percentage of ethanol in gasoline to 15 (E15). Bad idea!!

basilkies

Try changing gas stations, it is not unkown for them to mess with the pump readouts or water the gas.

Chevrolet Customer Service

There are many different factors that contribute to your fuel mileage but here are a few that GM has seen fit to outline that if checked and maintained properly will help you get better gas mileage.

Checking your tire pressure often and making sure that it is up to the required pressure is one of making sure that your engine isn't working too hard. Underinflated tires can create drag that your engine has to overcome and in doing so it uses more gasoline than normal.
Your air filter if dirty or clogged can serve to choke your engine or make it hard for it to pull in the required amount of air thus making your engine work harder. Check it often to make sure that it is not causing you problems.
The proper viscosity oil is also a factor in your gas mileage. Using the proper viscosity oil will help to keep the parts properly lubricated and will help the engine to not work harder than it has too.
Using Top Tier fuels (if possible) is another recommendation. Top Tier fuels have a detergent in it to clean out the fuel system while you are using it. Keeping the fuel system clean makes sure that the fuel moves through the system properly and is able to be burned properly for best effect.
Also using the recommended fuel octane is again another way to make sure you get all of your money out of your vehicle and your gasoline. Using a higher octane gasoline does not necessarily mean that your vehicle will get better gas mileage as your engine is not built nor tuned to handle or burn that fuel type which results in that your vehicle does not gain in performance nor gas mileage.
The final suggestion is to make sure that you get your spark plugs changed at the proper intervals. 100,000 miles is the general interval for most our vehicles and if your vehicle is near this mark changing the spark plugs will make sure that your vehicle is working at tip top performance. I hope this information helps you.

Jeff Morris, Chevrolet Customer Service