Wait! For cooking a good pasta:
1) Use a large pot with much more water than pasta.
2) When the water is boiling, add the salt then put the pasta. Stir it often with a fork or a spoon. This is important.
3) Do not overcook it.
4) AFTER you drained the pasta, you can add sauce/olive oil. Put olive oil during cooking won't help as Gofre said.
This issue is not really common with penne though. It is more usual with spaghetti or tagliatelle. Maybe the brand is important. May I suggest Barilla?