Panel Air Filters

A panel air filter replaces the paper element in the original airbox with a reusable performance filter. It is the least intrusive intake change: the standard ducting stays in place, nothing else on the car is altered, and a paper filter can go back in at any time.

The choice here is mainly the filter media. Oiled cotton gauze filters are cleaned and then re-oiled from a service kit; dry synthetic filters are simply washed and left to dry, with no oil involved. Either type is made to be cleaned and refitted many times.

Each filter is listed under the maker’s part number, which is the most reliable way to find the right shape and size. Use the number of the performance filter you are replacing, or the one the maker gives for your engine.

Check the fit before you close the airbox. The rubber seal should sit fully in the housing all the way round, or dirty air will get past the filter; clean out the airbox while it is open.

On an oiled filter, apply the oil evenly and let it soak in before fitting, because excess oil can be drawn onto the air mass sensor and upset its readings. Clean the element when it looks dirty or at the maker’s interval, and more often on cars that spend time in dusty paddocks or on unmade roads.