Reviewed By Paul B (Port Saint Lucie, FL) Reviewed for a 2008 BMW Z4 —2/23/2018 4:50 AM
K&N filters air to the proper degree. Paper filters restrict air flow by filtering particles too small to make any real difference. My mechanic says after cleaning don't bother to re-oil because it's almost impossible to replace the very light mist of oil of the original correctly. The multiple layers of cotton gauze are sufficient to protect your engine.