Ihave a 98 1500 4x45.9L 360 with 100k. I mostly drive a mix of highway, backroads, and town. No matter how nice i drive it i get about 12mpg. Is this typical for the 5.9L? any mod. suggestions?

 

How long have you owned the truck? When was your last air filter change? Tune-up? I'm assuming that you are current on you oil change. I did get between 15 and 17 mpg on a totally stock 5.9L, but I drive pretty consertively, and try to maintain a constant speed. I find that my mpg goes down dramitically when I really needed an air filter change, or if I waited too long on an oil change. I just upgraded to a diesel, so I've just sold the truck to a friend.