A gallon oil drain is a tool used to remove used motor oil from a vehicle's engine. It typically consists of a container or tank that can hold several gallons of oil, with a drain spout that can be inserted into the oil pan of the vehicle.

To use a gallon oil drain, the user will typically first raise the vehicle using a hydraulic jack or a ramp, and then locate the oil pan underneath the engine. The drain spout of the oil drain is then inserted into the oil pan, and the valve on the oil drain is opened to allow the used oil to flow from the engine into the container.

Once the used oil has been drained, the valve is closed and the oil drain is removed from the oil pan. The container of used oil can then be taken to a recycling center or an auto parts store for proper disposal.

Some gallon oil drains may also include a built-in funnel or screen to help prevent debris or contaminants from entering the container, and a cap to prevent spills or leaks during transport.

Overall, a gallon oil drain is a simple and effective tool for safely and efficiently removing used motor oil from a vehicle's engine. It is important to always follow proper safety procedures and disposal guidelines when using and disposing of used oil.