Abstract: A crankcase drain assembly comprising a manually operated valve unit mounted in the crankcase drain opening and a disposable container of flexible sheet material connected to the valve unit by a flexible hose member. The valve unit includes a large diameter planetary knob to facilitate manual opening and closing of the drain valve and eliminate the need for separate tools. The valve unit also includes a concave inlet port for seating in the drain opening so its rim area extends no further than level with the crankcase floor, thereby enabling the used crankcase oil to drain completely.