Well I have been using the TopSider to change my oil, after the initial two oil changes through the plug, and I have been right at 8.5 quarts get it at the full line. My personal experience has been that I have extracted more oil then pulling the plug while the car is on ramps; I am assuming it is because the car is level. With new cars the first couple of oil changes I like to drain the oil check the plug for metal shavings to see how the engine is breaking in.