My 08 Silverado can use as much as a qt of oil on long trips, about 500 miles.I normally travel at between 55 and 65 mph and use synthetic or semisynthetic oil. I currently have 82,000 Miles on the truck. There are no signs of an oil leak. After the trip I turned it off to unload the truck. When I started back up to put it away it blew out gray smoke.