Always clean the gasket sealing surface. An improper gasket seal is one of the most common causes of engine contamination. Make sure that all hardened dirt ridges are completely removed, both on the bottom and top of the air cleaner housing.
Check for uneven dirt patterns. Your old filter has valuable clues to dust leakage or gasket sealing problems. A pattern on the filter’s clean side is a sign that the old filter was not firmly sealed or that a dust leak exists. Identify the cause of that leak and rectify it before installing a new filter.