Oil Filter FAQs

As the name would suggest, the oil filter filters oil of solid particles before it lubricates the engine.

As the oil lubricates the engine, it picks up small metal fragments, dirt, and other grime that may be present in the engine compartment. It then returns to the sump to cool, and then is pumped by the fuel pump back through the filter and into the engine, so the filter needs to remove the contaminants the oil collected on its previous trip.

If the particles are large enough, they will stick in the moving parts of the engine, causing excessive wear. Over time, the particles and contaminants can also wear down the oil, which is why it needs to be periodically changed.

As the filter collects particles, it can become clogged. This can result in a buildup of pressure that can damage the filter and other components, as well as reducing the amount of oil to the engine. If the engine does not receive enough oil, the parts can wear prematurely, seize, or overheat. Before this can happen, however, the bypass valve will sense a buildup of pressure when working correctly, and will allow the oil to bypass the in-line filter and continue to the engine. But in this case, the oil will be unfiltered.

Most vehicles have the standard in-line oil filtration system mentioned above. You can, however, also look into bypass filtration systems. Bypass oil filtration systems are installed in addition to your in-line system, and allow a small amount of oil to bypass the in-line oil filter to go to the bypass filter, and then back to the sump before returning to the inline filter. Both inline filters and bypass filter systems will be graded with different efficiencies depending upon the size of particles filtered.

Bypass filtration filters particles of smaller sizes than traditional inline filters, and may remove other contaminants as well depending upon the system. The more thorough filtration can reduce the need for frequent oil changes, extending the life of the oil by as much as 5 times or more in some cases.

Fuel polishing goes beyond filtering the fuels. In addition to filtering, fuel polishing also removes water, acids, and other contaminants from the fuel. In some cases, additives can be included as an additional step in fuel polishing to help treat the fuel for certain problems, such as algae or bacterial growth or lack of lubrication.

Fuel that is stored in storage tanks may also benefit from filtering. As the fuel sits in the tank over time, it may collect a variety of particles and water that make it too contaminated for use. With the right bypass filtration system, the fuel can possibly be filtered and polished to a usable and even like new condition. In some cases, this can extend the life of the stored fuel from months to years.

Although fuel that has just been purchased has usually not been used, it can still be dirty, particularly if the fuel is cheap or of a lower quality. By filtering the fuel before it is used in equipment or machinery, it can greatly reduce the amount of filtering required of the filtration system in the equipment or machinery, thus reducing the need to change the filters as frequently.

Oil filters are rated by the size of particle that is filtered, called the micron rating, and by the percentage of particles at that size that are filtered, or the efficiency.

The media is the portion of the filter that performs the filtering. It can be synthetic or composed of cellulose materials. A composite filter is composed of both synthetic and cellulose materials. What the filter media is composed of depends upon the manufacturer’s preference.

For most vehicles, an in-line, or full-flow oil filter, is standard and acts as the primary filter. This filter filters the oil before it lubricates the engine, in order to remove particulates that can cause wear and tear on the engine components. In-line filters generally filter out particles anywhere from 10 to 40 microns in size, depending upon the filter efficiency.

A bypass filtration system is installed in addition to your in-line filter. As the oil flows from the pump to the filter and then to the engine, a percentage of the oil skips or bypasses the filter to enter the bypass filtration system. In the bypass filter, the oil is cleaned more thoroughly and sent back to the sump.

A bypass filter is capable of filtering particles of a much smaller size out of the oil, often as much as 1 to 5 microns in size. Some may also remove water due to condensation and other contaminates, such as acid, that can shorten the life of oil. By giving a more complete filtration, the life of the oil is immensely extended, increasing the time between oil changes by as much as five times or longer in some cases. The inline filters and bypass filter will still require regular changing.

Bypass filtration can also be called offline filtration, or kidney loop filtration. Kidney loop filtration refers to the way the system cleans the oil in a manner similar to the way kidneys clean the blood in the body.

Correct installation of a bypass filtration system does not invalidate a manufacturer’s warranty.