The K&N RU-5135 is a round-tapered, conical universal clamp-on air filter from K&N Engineering. It uses red cotton gauze media on a rubber top and a centered 2-3/4 inch inside-diameter flange. The manufacturer describes multiple layers of oiled cotton gauze designed to trap contaminants, and it markets the media for gains in horsepower and acceleration. Because the element is washable and reusable, it can be cleaned and re-oiled over its service life instead of being replaced like a disposable paper filter, which is the main reason to choose it over a stock box or a cheaper throwaway element.
Because this is a universal filter, the manufacturer does not tie it to a specific vehicle application, so the 2-3/4 inch flange must match your intake tube before you buy. The flange can be stretched up to 1/16 inch to fit in-between sizes. This makes the RU-5135 a practical choice for a track car, a custom intake build, or any engine where a factory filter box no longer fits. Searchers looking for a 2.75 inch ID round tapered cotton gauze air filter, a washable clamp-on intake filter, or a reusable universal conical air filter with a 5.063 inch base will find this part matches those needs.
The manufacturer states the molded rubber flanges can be stretched up to 1/16 inch (1.5 mm) to fit in-between sizes. Stretching beyond that range is not recommended by the manufacturer, so confirm your tube diameter first.
Yes. The manufacturer states K&N universal air filters are washable and reusable, so the element can be cleaned and re-oiled rather than replaced.
The manufacturer lists a re-oiling amount of 0.67 oz (20 ml) for this filter.
The RU-5135 is a slip-on, clamp-on filter, so installation involves fitting the rubber flange onto the intake tube and securing it, with the flange stretched slightly only if the tube falls between sizes. Measure your tube's outside diameter before ordering and compare it to the 2.75 inch flange. Clean and re-oil the element after the first install and at each service interval, using the manufacturer's stated amount of 0.67 oz. Specific tool requirements and the mounting procedure were not confirmed in the manufacturer documentation reviewed, so check the manufacturer's instructions before starting.
