Gm says the 1000 mile thing basically to keep from paying out so many claims. Think of that logic...your average person doesnt change oil bit every 5-6k miles. Thats 5qt low per oil cycle (granted your warning light would come on first), but under normal circumstances that woukd be absurd. Soccer moms would go through motors every 15k miles. Its not normal, its creative wording in owners manuals and warranty books to ssve the company money. We dealt with this with several new trucks/suvs during my time at gm and the vehicle owners did NOT buy into the whole normal oil consumption thing. 1qt per 3k miles would be somewhat acceptable.