I take it you mean air filter instead of oil filter? Take it out and if you are going to smack it against something to get most of the dirt/etc. out be sure you hit the side that faces out on whatever you are hitting. Do not hit the clean inside side of the filter against anything. When you hit the outside it will knock all the shit out, but if you hit the inside it will only push it in farther. You can also blow through it with an air hose which works really well, but again be sure you blow from the good clean side to the dirty outside side of the filter.
Life is short, but sweet for certain...
Life is short, but sweet for certain...