Used motor oil, or 'sump oil' as it is sometimes called, should not be thrown away as it can pollute water ways and soils. Although it gets dirty, used oil can still be cleaned and re-used.
When changing the oil in your car or other motors such as lawnmowers, boats or chainsaws, be sure to dispose of it correctly. Oil picks up hazardous contaminants when used in engines and can pollute water and soil. Pour your used motor oil back into an empty oil container and take it to your local used oil facility for recycling. Check with the facility as they may also accept your oil filters and oily rags.
Many council facilities such as transfer stations, waste management centres or landfill sites accept used oil. Household chemical clean out programs run by your council or state government may also collect used motor oil.