Fry guys,
Filtering your oil will definitely add to the life of your oil. The better you filter it the longer it will last. Your oil will last for months as long it is heated up to to 250 every 3 0r 4 weeks or so. The oil really doesn't go bad on its own, its the impurities from the turkey and your marinades that break down your oil and can go rancid over time. Heating will keep any "bad" stuff dead. Peanut oil is the best to use because of flavor. Soy bean oil is much better for you and less expensive. I mix the two to get the flavor and extend the life of the oil. You will definitely be able to smell and taste when it is time to change your oil, but I think it will last longer than most people would think. My $.02.