I don't know about the 6.2's sucking gas and having oil problems, I have a couple friends with them, and it looks like 18 to 19 average is what they are getting (driven decent) and NO oil problems at all. Yeaa, that's no 5.3 millage, but not all that bad for the added power.
I grew up with old 4x4 pu's too, in 1972 I bought my first one NEW, a Chevy 350 4 speed with posi front and rear, spl. ordered it and waited to get it, as I wanted that front posi. lol
Yeaa, they liked gas, but gas was only 20 cents a gallon around here!
BTW, I love my Silverado with its 5.3 V8.
DM