When you think air filter, think of the human lung,but when you think OIL FILTER think of the human kidney. This filter is essential to the long term life of your scooter engine. The oil filter eliminates all of the nasties that can run through your otherwise well running machine. It is designed to be replaced with each and every oil change / 'service'. Make a note that when you are changing your oil filter, to make sure to smear a small amount of fresh oil on the oil seal or the best seal. Hiflo oil filters are one of the biggest manufacturers of filters to the scooter industry, so you can rest assured its a quality product.