Here is a short EPA video on how to manage your used oil. You should always try to recycle your used oil. If you decide to dispose of your used oil, you must determine if it exhibits any of the four hazardous waste characteristics – ignitability, corrosivity, reactivity and toxicity. If it does, it must be disposed of as a hazardous waste.
Remember: Used oil is a RCRA “solid waste” and any solid waste that exhibits any hazardous waste characteristic is a hazardous waste.
In California, you must manage your used oil as hazardous waste (known as non-RCRA waste in California). Here is a guidance document on used oil management in California.