Hey what's up? First and cheapest is the PCV's, clogged would cause you to pressurize crankcase and force oil out dipstick. Next and you don't want to hear this but could be getting blow by, compression rings are going and causing the crankcase to be pressurized, which mean rebuild soon. If it only a little I would bet it is just the PCV's. When I blew my motor, broke two ring lands mid track and blew oil out dipstick, all over engine and down track. What a mess.