Of course oil doesn't work. Oil and water don't mix so all the oil will do is float on the top and achieve absolutely nothing. I know, I've tried it too, and all I see is globules of oil floating on the water. It does no good there. And anything you do to it after it's cooked is too late.
The Italians know best and what they do is cook it in a BIG pot with LOTS of water so there is plenty of room for the pasta to move. If it looks like far too much water, you're doing it right!
Bring the water to a rolling boil. Don't add salt yet because that makes it boil more slowly. When it's boiling, add salt (Anna Del Conte, the doyenne of Italian cookbooks in England, says "salty as the Mediterranean" - maybe that's going a bit too far but a good big shake is what you need), add the spaghetti, and keep it on a fast boil the whole time. That keeps it moving and stops it coming together and sticking together, and there's no need to stir it when the boiling water is doing that for you. When it's done, drain, mix with the sauce and serve IMMEDIATELY on hot plates - pasta will NOT wait.
While I'm at it, something Italians always do is keep some of the cooking water to add to the sauce. The starchy water helps it cling to the pasta. So don't drain your pasta too thoroughly - if it's still a bit wet, that's all the better.