All by people who change their own oil. Used oil and oil filters are banned from the landfill and dumping is illegal. Recycling is the only legal method of disposal. A single quart of oil will foul the taste of 250,000 gallons of water. And as little as one pint of used oil can create an acre-sized slick on surface water.
Oil kills the floating organisms in fresh water that feed fish.
And it kills aquatic life. We cannot afford to have our drinking water contaminated. Every one of us has to share the responsibility for transforming used oil from a liability into a major asset. Take it to a recycling center. There the oil is picked up for recycling.