It definately sounds like an oil leak. There are a number of places it could come from; Look under the car to see if there are any oil spots on the floor or driveway. If so, try to isolate where they are coming from. Valve cover gaskets are logical but not necessarly from not being run. I bought a car that had been in storage for 28 years and it had no leak when I got it started. It could also be transmission fluid or the ower steering leaking. Somewhere you are losing oil. NOW, there is one more possibility... rotten gas. After four years, it is probably rotten.