Recycling automotive fluids
by Larry Wagg

The fluids used in automobile engines are generally quite hazardous. Oil and transmission fluids are very sparingly soluble in water (on the order of 50 parts per million) which means that a very small amount of oil may contaminate a large volume of water. Small spills may persist for many years since they enter the water table so slowly. Ethylene and propylene glycol, used as antifreeze, mix with water and therefore are even more mobile than oil when they enter the environment. Ethylene glycol is very toxic, and since it has a very sweet taste, hundreds of household pets die every year in North America from consuming antifreeze.

The hazards associated with these fluids are increased once they have been used in an automobile. Metals such as molybdenum from greases, copper and zinc from worn internal engine parts, and tin and lead from radiator solder will dissolve in these fluids. Combustion byproducts and unburned gasoline fractions such as benzene dissolve in oil, and many of these compounds are carcinogenic. Many combustion products are acidic, rendering the used oil corrosive as well as toxic.

Most fluids can be reprocessed, and in many cases re-used in their original applications. Antifreeze can be filtered, neutralized, and distilled to recover the pure glycol, which can be reused with no compromise in performance. The reprocessing equipment is simple to build and operate, so small systems are available to allow on-site reprocessing at garages and service centers.

Engine oil, however, is changed chemically due to the harsh conditions to which it is exposed, so the reprocessed oil will have inferior lubricating properties and will therefore have to be used in less demanding applications. Recycling engine oil is a much more complex process than distilling antifreeze; a large fraction of the used oil collected from automobiles is simply burned as fuel. Still, approximately 65 million gallons of re-refined oil are sold in the United States each year.

The market has grown to the point that many innovative solutions have found a niche. As an example, a small company in Nova Scotia operates a mobile oil purification system for lubricants, hydraulic fluids and dielectric oils used by industry. A relatively simple process, the system heats the oil under vacuum to boil off dissolved water and VOCs (volatile organic compounds), then the oil is filtered and returned directly to the reservoir of the equipment. Reprocessing on-site minimizes the risks associated with transporting hazardous materials. Visit their web-site at

http://atlenv.bed.ns.doe.ca/success/012.html

For an exhaustive bibliography of reports, articles and other references related to this topic, refer to a site maintained by Information Services of Dartmouth NS

http://www.nsrfc.ns.ca/infosvcs/wasteoil.html

Advanced oil filters have recently been introduced, manufactured with very precise control of pore sizes in the filtration media. These filters provide both higher energy efficiency and improved removal of solid particles, affording greater engine protection than traditional paperelement filters. More extravagant performance claims are made for other products; see

http://www.nas.com/~westg/BizOp/Stuart.html

The use of advanced engine oil reduces your impact on the environment in two significant ways. The product lasts longer in your engine so that your overall generation of used oil is reduced (oil changes at 7,000 miles instead of 3,000). Secondly, since the synthetic oils maintain their important properties better than standard oil, engine wear is reduced and the engine will last longer. Better filtration through the use of and advanced filter will reduce wear even further.

Tips for fuel economy can also help to reduce oil consumption. Plan errands so that you make several stops on the same trip. Cold engine starts are responsible for the majority of wear over an engine's life, and cold parts allow more oil to sneak past rings and seals, while unburned hydrocarbons from the poor combustion decrease oil viscosity and increase its vapor pressure.

Where to Recycle your Automotive Fluids on Campus

Antifreeze

Antifreeze is reprocessed on-site and reused in Mines vehicles. Used antifreeze (both ethylene glycol and propylene glycol) may be dropped off at the vehicle maintenance shop behind XXX Maple Street. Remember that this includes glycol used in laboratory temperature baths!

Engine Oil

Used engine oil is collected at the vehicle maintenance shop and periodically collected by Mesa Oil who re-refines the oil for sale as bulk lubricant.

Transmission Fluid

Due to the low volumes of transmission fluid generated, used fluid is combined with used engine oil for recycling.