2008 silverado 2500hd 6 speed auto

[deucy67]

i have 2008 silverado with 6.0, 6l80e trans. it shifts kinda fast. has anyone bought any programmers for them yet? also gas mileage...... it has 3.73 posi, and i thought with the 6 speed i would have gotten decent mileage. it is a crew cab, so i know it is heavy... but i get 10 mpg around town and like 12.5 on highway. anyone?????????????

[j cAT]

Originally Posted by deucy67

i have 2008 silverado with 6.0, 6l80e trans. it shifts kinda fast. has anyone bought any programmers for them yet? also gas mileage...... it has 3.73 posi, and i thought with the 6 speed i would have gotten decent mileage. it is a crew cab, so i know it is heavy... but i get 10 mpg around town and like 12.5 on highway. anyone?????????????

this mpg is way off after 10-15,000mi you should get 16mpg on hwy at 65mph.....i know of 2003 6.o 2500 that has over 100,000mi and thats what he gets.....so something is wrong.....at 65 mph how many rpm's are you turning...? make sure you have the correct tire pressures get a good gauge and i believe your tires will require 80psi ...?