I have had a K&N Typhoon SRI in my Element for quite some time now, but the filter always seems to look dirty. I can barely see any red and it usually has black coating. I clean it 2-3 times a year since it said that it doesn't need to be cleaned that often. By clean it I use the recharger kit and follwing the cleaning and aerosol directions throughly. Should I be doing something differently? Or is this normal?