aFe POWER Air Filter Oil is a proprietary formula made exclusively for aFe POWER's cotton gauze filters. Use of high quality oil that is free of contaminants means less chance of damaging sensitive vehicle electronics. These air filters are washable and reuseable, so proper maintenance is key to maintaining their performance. Always use oil with these filters as its' ability to protect your engine is severely compromised without it; the oil acts like a magnet to attract dust, and causes the cotton fibers to swell to capture larger particles. Paired with the aFe POWER Air Filter Cleaner, you have a complete air filter restoration solution.