2001 3500HD 8.1 help

I have a 2001 3500HD 8.1 automatic, service truck with 13K miles and the warranty will be expiring in a month. It is still burning a qt of oil every 700 mi. It is getting 7.6 mi a gallon in town and 9 highway. Does anyone know of computer upgrades that the dealer would do if i complain about a problem? They wont do the upgrades if im not complaining about a problem. They did do the heating system software upgrade for me because i complained about warm air coming out when the dial was turned to cool. My computer got free upgrades so why cant my truck? Is there a GM mechanic out there with access to their computer? Can anyone help me here with these 3 concerns? Also where is the pcv valve located on this motor? Thanks in advance!!!

Isnt there any sharp mechanics from a dealership reading this forum? My truck is more than just a truck to me, everythink i have depends on it.