Everything You Need To Know About Oil Filters in Car - Function & Design

Everything You Need To Know About Oil Filters in Car - Function & Design


Modern internal combustion engines need premium lubrication to run smoothly. Engine oil is not required to meet stricter-than-normal requirements for improved engine performance and extended service intervals. First, the quality of the oil filter used plays a vital role in preventing damage caused by dirt particles, soot, or unburned fuel in the oil.

During the combustion procedure, both dirt particles and combustion residues in dust, metal residues, and oil carbons causing its contamination and condensation. This results in increased fuel consumption and premature wear. The worst-case scenario is the risk of damage to the engine. Consistent engine performance can only be achieved if the oil is clean. Therefore, the oil filter is used to clean engine oil consistently and reliably throughout its lifetime. The reduction in fuel consumption and the accompanying increase in engine performance, high-performance oils, and new problems cause additional qualifications to be sought in oil filters in vehicle production.

Manufacturing trends are going towards compact oil filters, which are integrated into the engine and perform more tasks besides filtration. These filters feature metal-free oil filter elements made with the latest filter media to achieve consistently maximum performance values, even during extended change intervals.

From a functional point of view, oil filters can be divided into two groups: entire flow filters and combined full-flow / bypass filters. Full flow filters are installed on the oil circuit so that the oil is cleaned during each cycle. In combined full-flow / by-pass filters, approximately 90 – 95% of the oil flows over the paper star of the full-flow filter, while about 5-10% flows through the bypass filter or bypass centrifuge.

Since the usage areas and requirements of oil filters can be very different, these filters have very different designs:

Spin-on oil filters (screw oil filters)

Due to their effective filter performance, screw oil filters have been a critical component in oil filtration for years. It is reliable and easy to install. Screw oil filters can be used in both full-flow filtration and bypass filtration.

Compact oil filter modules

The cleanliness and temperature of the oil play an essential role in the reliability and operation of modern engines. With the function of filtration and cooling, compact filters are increasingly used for continuous monitoring of these two factors. Permanently integrated into these modules are a bypass valve, a return check valve (check-valve), a threaded oil cooler, an electrically controlled cooling thermostat, alternator cooling preparation, a filler neck for oil filling, or an oil pressure switch.

Thanks to high-performance plastic, the compact design of these modules saves installation space, reduces weight, and contributes to fuel savings. The module's design requires filter manufacturers and engine design engineers to work together to optimize the integration of the filter placed in the engine block.

Replaceable oil filter elements

The replaceable oil filter elements are the truly replaceable part of the oil filter module. As the module and its attachments are permanently attached to the engine block, the filter element is replaced at prescribed intervals throughout the vehicle's entire service life. The filter element is environmentally friendly as it is entirely thermally recyclable. Unlike the screw oil filter with a metal body, it can burn without leaving any residue.

Special Designs

Specially designed filters are also available for special applications such as transmission oil coolers.


An appropriate performance spectrum characterizes high-quality oil filters to meet the needs of the respective application. Their features are:

  • In addition to being resistant to corrosion, it is a stable housing against pressure and pulsation.
  • A consistently very strong filter material throughout its entire service life
  • A return check valve ensures that the filter and oil channels are not run dry when the engine is off, ensuring that oil is delivered quickly when the engine is started.
  • A bypass valve ensures the oil supply during the cold start phases and in case of excessive lengthening of change intervals and excessive contamination of the oil filter.
  • Safe mounting and tight connections.

Environmental Protection

One of the most important reasons vehicle manufacturers cooperate with mineral oil and filter manufacturers is to extend oil change intervals for environmental and service-friendly protection. As a result, change intervals of 20,000 to 35,000 miles are not unusual in today's passenger cars. However, it is vital to replace the filters at regular intervals. A new oil filter will refresh the system to absorb solid particles and allow the oil to flow unhindered in the oil circuit. As a result, besides protecting the environment, it saves fuel and money.

Brand manufacturers produce oil filters by the strictest environmental rules. Universal retrieval systems ensure spin-on oil filters are recyclable. From an ecological point of view, metal-free filter elements (used in oil filter modules) are a better choice. The less raw material is used in its production, less waste is generated in service and maintenance work, and a significant reduction in environmental impact is achieved through improved disposal processes.


Wear rates are reduced by modern oil, and filter systems are adapted accordingly. In this context, the filters and oil work together in the oil filters, which are responsible for removing the particles accumulated because of contamination and wear in the oil circuits.

If the filtration is not sufficient, the mixture of oil and dirt creates a hazard to the engine over time. Particles penetrate narrow bearing clearances as they cause gradual wear of pistons, bearing bushings, and bearings. You can avoid these risks with OE quality oil filters, regular oil filters, and engine oil changes. The performance and value of the engine and the vehicle are thus preserved in the long run.