You'll have to do some hunting, but by and large the best places I've found are asian restaraunts. They usually change their oil frequently, so it's pretty clean. Stay away from fast food joints like McDonalds, cause they have a lot of animal fats which cost more to filter and make into bio. Just make sure that where ever you get it from that you're not "stealing" from a current contractor that's taking it already. This day and age it's hard to find a restaraunt that isn't already contracted.