09 ccsb, 5.3l with VIN code M. i believe this is the Al block. using ~1 quart in 5000miles. went through the pvc breather/ valve cover/ fouled plugs routine at about 40k. Blackbear tune at about that same same, including disabling the afm. oil consumption improved slightly but remains at ~.75 quart per 5k. no formal oil consumption test but am planning to do one. using mobil 1 syn and lucas oil syn oil stabilizer. 65k miles on the truck currently.