The K&N RU-5100 is a red, round-tapered universal clamp-on filter with cotton gauze media, offered as a reusable alternative to disposable paper elements. The manufacturer lists a 3-1/8" flange inside diameter, a 6" base, a 5" top and a 7" height, so fit depends on matching your intake tube rather than a specific airbox. Owners on user forums point to reusability as the main appeal, since the element is cleaned and re-oiled rather than replaced.
The purchase case rests on durability and running cost more than power. The manufacturer rates the filter at up to 99% overall efficiency, and the washable media turns a recurring paper-filter expense into a one-time buy. Forum reports on horsepower are mixed: one 4Runner owner didn't notice any performance gains, MPG losses or dirt/dust past the filter, while a Tundra owner found that the OEM paper had much better air flow. Because the manufacturer treats this as a universal fit, confirm flange and body dimensions before ordering. Search terms: round tapered cotton gauze air filter, 3-1/8 inch flange washable intake filter, reusable clamp-on K&N universal filter.
The manufacturer's listing for this part identifies it as a universal-fit filter, not one tied to a single model. Check the flange and body dimensions against your intake tube before ordering.
The manufacturer lists a re-oiling amount of 1.36 oz (40 ml) for this filter. Apply light, even coverage, since owners on user forums warn that excess oil can cause problems.
Yes. The manufacturer lists this filter as washable.
This is a clamp-on filter, so the job is mostly fit-checking and clamping. Measure your intake tube before buying, because the 3.125 in flange inside diameter and 1.75 in flange length are the numbers that determine whether it seats. Tighten the clamp evenly to prevent unfiltered air leaking around the flange. Owners on user forums warn against over-oiling, saying that the oil could dirty up the MAF sensor, so keep the element lightly oiled and wipe off any excess before reinstalling. Follow the instructions supplied with your intake for torque and clamp placement.
