The K&N 33-5108 is a washable, reusable panel air filter built on K&N's High-Flow design: layered, oiled cotton-gauze media in a flexible frame that drops into the factory airbox. The manufacturer lists it for the 2020-2026 Hyundai Sonata with the 1.6L L4 application, and K&N's own 2.5L Sonata pages also list this part number, so confirm your engine before ordering. Compared with a stock paper element, the oiled media is designed to raise airflow while still trapping contaminants, and the manufacturer says the filter is engineered to increase horsepower and acceleration.
Compared with a cheaper disposable performance filter, this one costs more up front but is cleaned and re-oiled rather than replaced, and the manufacturer backs it with a No-Hassle Lifetime Limited warranty. Owners on user forums commonly clean their K&N filters about every 50,000 miles. Search terms this part answers: 2020-2026 Hyundai Sonata 1.6L reusable air filter, K&N 33-5108 drop-in intake upgrade, washable high-flow cotton gauze filter, Sonata stock airbox replacement.
Installation is a drop-in job, but the manufacturer notes that some K&N filters should be seated into the airbox lid first, and that K&N clips need more closing pressure than a foam-sealed OEM element. Don't force the lid: if it resists or the airbox bends, stop and recheck the filter's seating. The oiled element should also be cleaned and re-oiled at service intervals to keep its flow characteristics.
The manufacturer's listing names the 1.6L L4 application, but K&N's own 2.5L Sonata application pages also list part 33-5108. Confirm your engine and model year against the manufacturer's fitment lookup before ordering.
Owners on user forums commonly clean it about every 50,000 miles. The manufacturer specifies a re-oiling amount of 1.18 oz (35 ml) after cleaning.
The manufacturer lists a No-Hassle Lifetime Limited warranty for this filter.
Per the manufacturer's installation hints, some K&N filters must be installed into the airbox lid first. Hold the element in place with your fingers while reinstalling the lid so it doesn't fall out. Disconnecting the intake tube from the airbox lid can make the lid easier to maneuver, especially if the tube is rigid. Owners on user forums describe the swap as simple: remove the old element, drop in the K&N, and close the box. Because K&N clips need more pressure than OEM foam-sealed boxes, seat the lid fully before fastening, and stop if the airbox bends. Specific tool requirements were not confirmed in research.
