No its not normal your getting blowby your pcv system do to crank case pressure don't just put a filter on the one side to do it wright you would put a little filter on your valve cover where you have a hose going to your intake tube and cap off the intake tube and in the middle of your valve cover get rid of your pcv valve and put an elbow fitting and put another filter on it and then put a cap on your intake manifold where you pulled the hose off by doing that you bypass the pcv system.