Contact the waste management authorities in your area for information about how to properly dispose of used motor oil. Your city, township or state should have disposal facilities. This article has a lot of helpful information: http://www.ehow.com/how_2282844_dispose-motor-oil.html
Motor oil is toxic to plants. Never dispose of motor oil near plants.
Most auto shops recycle their oil, and those that do DIY oil changes should recycle or dispose of their oil properly through household hazardous waste (HHW) facilities, auto shops or other collection sites.
Take it anyplace that recycles oil. Almost all Auto Parts stores, or WalMart.
The bottom part of the engine is the oil pan. There will be a drain plug on it, remove drain plug and oil will come out; properly dispose of oil.
Take it to anyplace that accepts used engine oil for recycling. Walmart, and most auto parts stores.
Take it to your local recycling centre
In many areas recycling is compulsory. One must also properly dispose of chemicals such as spent motor oil and antifreeze. Morally and Economically it is only logical to try to consume as little energy as possible.
You can dispose them at any oil and gas stations
Motor oil is used to run cars. Cars add pollutants to the air when they are running. This is how motor oil can be harmful to the environment. It can also kill plants and animals if not gotten rid of properly.
Set them on a drain pan inverted for 24 hours, crush them, then dispose of them. If you don't work in a shop where you have such a setup, auto parts stores should be able to dispose of them at no cost to you.
It depends the motor.
A 350 Motor needs 5 qaurts of oil to function properly