Eliminating Vehicle Oil Changes and/or Oil Filters Disposal

Two major sources of pollution are (1) used oil drained from various types of engines and (2) used oil filters. These pollutants contribute to soil, surface water, and groundwater contamination if not properly managed. Vehicle motor oil is typically changed on a routine basis, usually either at mileage or time intervals. As a result, billions of gallons of used oil and millions of used oil filters are generated each year in the U.S.

Oil itself does not "break-down." Oil changes are necessary because additives deteriorate and contaminants build up and contribute to reduced engine life. The most damaging contaminants are particles less than 10 microns (mm) in diameter.

This Fact Sheet presents two technologies that reduce or eliminate the frequency of oil changes and the generation of used oil filters and could completely eliminate both these pollutants.

By-Pass Filters

Vehicle engines are usually equipped with "full-flow" filters to remove particles from the oil that otherwise could damage the bearings, etc. These filters remove only particles of grit, etc., that are about 40 mm and larger in size. They do not remove other contaminants such as water, fuel, and gases that become present in engine lube oil systems as the engines operate.

The "by-pass" filter does not replace the full flow filter: it is installed in addition to and in parallel with it. About 10 percent of the total oil flow is diverted through the by-pass filter in a continuous cycle. The by-pass filter cleans the oil by removing particles larger than 2 microns (most engine damage is caused by particles smaller than 10 microns), as well as the detrimental water, fuel, and gases. This 10-percent oil flow is then returned to the oil pan. As a result, most of the contaminants in the oil are filtered out, and the oil will not need to be changed. Oil may need to be added, as necessary, to replace the amount lost during engine combustion. The by-pass filter not only eliminates the need for oil changes, it also should extend engine life as these contaminants are removed.

The Department of Defense, some truck fleets, and a few North Carolina state agencies are investigating the use of by-pass filters. In addition, the Society of Automotive Engineers conducted a 12-year study on the use of by-pass filters in school buses. The results from these various tests continue to be positive. It is important to note that these filters have been used in critical-service marine engines for several years, including those of the major oil companies. Although the oil itself will no longer need to be changed, the filters, both the full-flow and the by-pass, will need to be changed periodically. A current test on one diesel fleet shows that the full-flow filter on each vehicle will need to be changed/cleaned only about every 40,000 miles, and the by-pass filter per vehicle should be changed/cleaned only about every 15,000 miles.

Typical By-Pass Filter

Based on analysis of the oil, these intervals have already been lengthened and will continue to be increased as appropriate.

To date, the average oil life for this test series has been 130,000 miles. The current results indicate that this fleet would reduce its oil consumption by 40 million quarts per year and realize a very good financial benefit from a payback of less than 6 months on its capital outlay. Although definitive estimates on the extended lives of engines have not been made, the current expectations are in the 1.5 million-mile range.

Reusable Oil Filters

Reusable full-flow filters are similar in size and shape to the disposable full-flow filters commonly used. The main difference is the filter media. The reusable filter contains a metal media instead of the more common paper media. The metal media can be removed and cleaned quickly and easily and then re-installed in the same filter housing. The cleaning process involves circulating or soaking the filter in a cleaning fluid and then blowing it with compressed air.

With the reusable filter, oil still needs to be changed routinely although the intervals between changes may be extended. Currently, reusable filters are available only to replace the full-flow filter; however, a reusable by-pass filter probably will be developed in the future.

Warranty Concerns

A primary concern with the use of either type filter is the effect it would have on vehicle warranties. Filter manufacturers and vehicle manufacturers have discussed this concern extensively. The position of the vehicle manufacturers is usually that if an engine problem can not be directly attributed to an oil filter, the warranties remain in effect.

The North Carolina Division of Pollution Prevention and Environmental Assistance provides free, non-regulatory technical assistance and education on methods to eliminate, reduce, or recycle wastes before they become pollutants or require disposal. Telephone DPPEA at (919) 715-6500 or 800-763-0136 or E-Mail for assistance with issues in this Fact Sheet or any of your waste reduction concerns.

OWR-96-34. August 1996.