To me a vehicle down 2 quarts of oil, even with a 9 quart sump indicates to me, neglect. It shouldn't be down 2 quarts if the owner cared for the vehicle and took care of routine maintenance, checking the oil level and tire pressure tops the chart for basic maintenance. Regarding the dealer letting the OP take the vehicle overnight, I don't see a problem with that. What I see is a stupid dealership. Any car we ever sold or allowed a customer test drive went through the shop first, there would be no way they'd be low on oil. Having said that, the vehicle might very well be fine. However that's a risk not worth it to me, knowing it was low on oil, and arriving at the 16K mile figure the OCI "might" have been.