While the popularly put forth solution to clean plastic motor oil bottles is to use a mixture of dish soap and water, the reality is that this will not clean the bottle at all. A water/soap mixture will create even more waste material that cannot be disposed of without special treatment. The real problem is that the oil in the HDPE plastic bottles seeps into the plastic itself. In order to clean plastic motor oil bottles you need a highly specialized CO2 pressure treatment system. They are available for purchase at great expense and can fit in the back of a pickup truck. If you are thinking of becoming a professional recycler of plastic motor oil bottles here is a quick overview of the steps involved.
Allow all the visible motor oil in the plastic bottle to drain into an appropriate receptacle.
Place the bottle in the injection vessel of your pressurized CO2 system. Seal the vessel and engage the system to fill the vessel with liquid CO2. Follow the manufacturer's instruction for the time to leave the liquid CO2 in the vessel.
Open the valves to allow the CO2 gas to escape the injection vessel and condense in the reclamation vessel. The liquid CO2 will have absorbed the oil that impregnated the plastic of the motor oil bottle and removed it from the plastic. The CO2 will then become an oil/gas that will fill the reclamation vessel.
Engage your machine to change the pressure/temperature in the reclamation vessel to allow the CO2 gas to liquefy and release the oil into the vessel. Dispose of this oil properly. Remove the clean plastic bottles from the injection vessel and recycle them according to HDPE standards.
