In these parts the 4.8 in the nnbs trucks are by far the most common engine, easy... Just about any dealer around here all have 4.8's
Also I have seen posts from mechanic at GM dealers across north america the 5.3L engine was terrific until they ruined it with AFM, it's a joke of a system that GM screwed the pooch with
Re: My truck has the infamous 5.3L oil consumption problem.
The AFM system is a joke on these engines. we see issues with them on a regular basis. which would be daily. anyways, 2 different fixes. depending on what they do, you will either have the pistons and rings replaced, and possibly have AFM lifters replaced as well, and a new VLOM, and oil deflector installed. or, they will do the piston soaking with Top engine cleaner, and install the oil deflector. more than likely, probably remove engine, replaced rings and pistons. depending on which cylinder(s) is the issue, may need lifters as well. im sure they will replace the VLOM.
oil doesnt have an affect on it, so conventional or synthetic doesnt matter. they burn oil either way. one thing i would do, always change oil every 3000 miles. regardless of oil life monitor. do not follow the oil life monitor. it is inaccurate.
be glad yours doesnt knock, see a few in for that problem as well, or misfires. camshaft failure, lifters, etc...
the engines were great until they added AFM to them. since then it has created nothing but problems. and it doesnt just affect the trucks. its across the line, W body, S/T, C/K, etc....
http://www.gminsidenews.com/forums/f53/my-truck-has-infamous-5-3l-oil-consumption-problem-106584/