Had the same problem on my '04 Summit, leaked oil like a s.o.b. Bought the oil reservoir insert from Dan on dootalk.com. I was really surprised when I installed the insert how out of round my reservoir opening was! Needless, to say the insert fixed all my oil leaking problems. Simple fix for a pain the the neck problem. I read all the other remedies out there like using a Polaris cap or wraping the threads with black tape and all I can say is I'm glad I didn't waste my time with them. The insert works and it is worth every penny. Here is a link to the dootalk store
http://www.dootalk.com/dtproducts.php. Just scroll down about 3/4 of the page, it's called an Oil Reservoir Delrin Insert and it will cost you $16. Good luck to ya!!!!