Facts About Used Oil Disposal: Harmful Ingredients

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Used oil disposal has serious human and environmental effects. What harmful ingredients can be found in used oil?

It is estimated that less than 45% of used engine oil is being collected worldwide while the remaining 55% is thrown by the end user in the environment. Auto repair shops are among the highest contributors of improper used oil disposal.

Auto repair shops are a common feature of countries that are at the receiving end of second-hand or used cars in many Asian countries. As used cars expectedly do not work efficiently due to parts that are at the verge of their usefulness, this requires frequent visits to the mechanic. As more used cars flood many Asian countries and as cars become cheaper, these cars also require more maintenance works to keep them running.

Among those common maintenance works performed by car or small vehicle repair shops are engine overhauling and oil change. Engines have to be rebored and sleeved to bring the car's  piston to its original size. For both old and new cars, regular replacement of degraded oil has to be done to keep the engine running smoothly.

As a result of these maintenance works, waste oil disposal by these small repair shops becomes a concern. Waste oil disposal is taken lightly by many users and handlers partly due to their ignorance of the ill effects of improper disposal and partly due to lack of clear environmental guidelines and weak enforcement of environmental laws aimed towards the management of oil wastes. Mechanics in repair shops or the self-servicing vehicle owner just dispose of their wastes directly into the drain, unmindful of the possible human and environmental consequences.

Oil disposal drain in one of the small vehicle repair shops.

How can oil handled by mechanics and disposed into the drain affect them and the environment? Is this really a matter of serious concern? What are the ingredients in oil and how can this be harmful to humans?

Used Oil Composition

Karachi University in Pakistan analyzed used motor oil samples from across the city. They found out that the average level of concentration of different metals found in the samples was: lead 110ppm (parts per million), zinc 685ppm, barium 18.1ppm, arsenic 5ppm, cadmium 2.5ppm and chromium 3.2ppm. The soil contaminated with used motor oil had about 100ppm arsenic, 20ppm cadmium, 1,800ppm lead and 285ppm barium. The relatively high concentration of metals in contaminated soil is due to accumulation of these metals.

The above metals are harmful ingredients found in many synthetic oils. All these metals are highly toxic with carcinogenic and teratogenic effects. Carcinogenic substances are substances that can cause cancer because of their ability to damage the cell or interfere with its normal metabolic processes. Teratogenic substances are substances that can interfere with normal embryonic development. Exposure is through direct contact and through ingestion via the food chain.

This means that the harmful metal ingredients contained in used oils can increase the incidence of cancer among humans as well as lead to increased cases of abnormal babies. Continued exposure to these substances can, therefore, be dangerous as these can directly and indirectly affect people. 

Practical Steps to Avoid Exposure

Knowing these things, what practical steps or actions then should be done? While there are many don'ts and preventive measures that can be recommended to people who are handling used oils in auto repair shops, foremost among the measures should be to dispel these workers', as well as self-servicing vehicle owners', pathetic attitude.

The author observed that while there is a common warning found in the labels of engine oil containers, seldom do mechanics or users in general, if ever, read the important information contained therein and take necessary precautions, i.e., to avoid exposure to and dispose of properly the used synthetic or mineral oils.

To avoid being subjected to the harmful ingredients in used oils, some precautions can be undertaken. There are many oil-resistant gloves created for the purpose and these should be worn all the time while working with engines to prevent the direct effects of used oil. And there should be available oil disposal or collection tanks in fuel stations for the purpose as used oils can be recycled.

This will require, therefore, an effective campaign among mechanics in auto repair shops and general users to handle used oils carefully and inform them of ways to dispose of these hazardous substances properly. Who should do the campaign? Everybody who reads this and gets the opportunity to do so.


Chapman, G., 2009. Used oil and its effects on the environment. Retrieved on April 20, 2010 at http://www.articlesbase.com/automotive-articles/used-oil-and-its-effects-on-the-environment-876009.html.

Hamad, B. S., Rteil, A. A. and M. El-Faddel, 2003. Effect of used engine oil on fresh and hardened concerned. Retrieved on April 20, 2010 at http://www.highbeam.com/doc/1G1-104970182.html.

Ilyas, F., 2009. KARACHI: High metal content of used motor oil poses hazard to public health. Retrieved on April 21, 2010 at http://www.dawn.com/wps/wcm/connect/dawn-content-library/dawn/the-newspaper/local/karachi+high+metal+content+of+used+motor+oil+poses+hazard+to+public+health.

Longhurst, C., 2010. The not-so-clever classic oil additives. Retrieved on April 21, 2010 at http://www.carbibles.com/additives.html.

©  2010 April 21 Patrick A. Regoniel Facts About Used Oil Disposal: Harmful Ingredients


Lindsey Lewandowski
Posted on Jun 12, 2011
Johnny Dod
Posted on Apr 21, 2010