What is an oil filter and what is it used for and how to choose

During maintenance, vehicle owners are faced with the problem of an oil filter for an automatic transmission engine. The oil filter resource does not have specific values, and they are changed together with engine oil, depending on the maintenance schedule. About what filters are, the principle of operation and how the oil filter works, and how to change it - read on.

What is an oil filter

The oil filter is a device that cleans the oil from mechanical impurities and chips, while maintaining its properties during the entire period of operation. The filter prevents the conversion of oil into an abrasive mixture that adversely affects the friction surfaces of lubricated parts.

The filter consists of the following elements:

• the housing (if the glass is not provided in the engine) has several inlet openings and one outlet with a mounting thread;
• body sealing gum;
• filter element, which is made of special paper with a certain bandwidth, trapping dirt and other particles. To increase the working surface, the paper element is compressed into an accordion, and also has a special impregnation that does not allow paper to deteriorate under the influence of oil;
• bypass valve. The most important part of the filter, preventing oil starvation of the engine. Cold oil is more viscous, the filter capacity is insufficient, so the valve bypasses the oil, following the logic that the unit will work better on dirty oil than without it at all. Upon reaching the operating temperature, the oil is filtered;
• an anti-drain valve is necessary to prevent the oil from draining back into the filter, so that when the engine starts, oil flows instantly to the rubbing parts;
• spring holding the valve with the engine off.

How the oil filter works: principle of operation

The principle of operation of a standard filter is simple: when the engine starts, the oil pump starts to take action, which takes oil from the sump. The heated oil enters the filter housing, passes through the paper element, then, under the influence of pressure, enters the oil channel - circulation occurs all the time the internal combustion engine is running. The filter comes into operation at a pressure of 0.8 bar.

By the way, an anti-drain valve may break on poor-quality filters, because of which the oil pressure indicator will blink on the instrument panel for several seconds. The lamp goes out as soon as the oil begins to pass freely through the filter. In this case, the filter element must be replaced, otherwise oil starvation will increase the wear of the rubbing parts.

What are oil filters

Oil filters have many modifications, they differ not only in size and the presence of a housing, but in the cleaning method:

• mechanical - the most common, has a simple design;
• gravitational. A sedimentation tank is used here, by the way a striking example is the Volga ZMZ-402 car engine, where such a filter is used. The filter element is inserted into a metal casing, which is also a sump. This allows you to minimize contamination of the filter, leaving coarse particles on the walls of the housing;
• centrifugal. It is used on trucks and other commercial vehicles with high volume diesel engines. A rotor and an axis are used in the centrifugal filter housing. The oil is pumped into the centrifuge through the holes of the axis under high pressure, due to which the oil is quickly cleaned by expelling the dirt.

How to choose an oil filter

Most oil filters are similar to each other. The vast majority have a wide interchangeability, especially for engines of the same make of car. Correctly select the filter element will allow the electronic catalog of spare parts for your car, where you will find the part with the necessary catalog number. If your plans do not include the installation of the original filter, then by this number any spare parts catalog will give you analogues.

By type of construction: here you can see by eye which filter is installed on your car, most often it is a cabinet or insert. The second type should be equipped with a sealing rubber to seal the case. 

Cleaning method: more commonly used mechanical type. For passenger cars, this type copes with the task, especially if high-quality oil with minimal waste is used.

Thread type: metric or inch. Metric will be indicated as “M20x1.5”, where “M20” is the thread thickness, and “1.5” is the pitch in mm. Previously, the inch type (American standard) UNC - coarse pitch and UNF - fine pitch prevailed, for example 1/2-16 UNF means half an inch thread with a pitch of 16 threads per inch.

Throughput is an important factor. The nuance lies in the fact that spare parts catalogs often select filters according to the dimensions and thread diameter, without taking into account the throughput. Example on an Infiniti FX35, V6 VQ35DE engine: the parts catalog gives the original number 15208-9F60A. This filter works well with 1.6-2.5 engines, it is not enough for a 3.5-liter engine, especially in winter, the engine starts to work for a long time without a filter. Soon this leads to the failure of the motor due to the fact of running on dirty oil. 

According to the characteristics of the throughput, a filter 15208-65F0A is suitable, which works as expected. Therefore, pay attention to the size of the filter and its characteristics. 

Filter Manufacturers and Packers

According to many years of experience, car enthusiasts and service stations have brought out the best manufacturers of oil filters: 

• original - the manufacturer of the same name, guaranteeing 100% compliance with the characteristics and quality;
•  Mahle/Knecht, MANN, PURFLUX are reference manufacturers who are responsible for the quality of products and specialize only in filter elements;
• Bosch, SCT, Sakura, Fram are the best manufacturers in the price-quality category. From experience, such filters also fully cope with their duties;
• Nevsky filter, BIG FILTER, Belmag - inexpensive Russian manufacturers, can be installed on domestic cars, as well as old foreign cars;
• packing firms - Nipparts, Hans Pries, Zekkert, Parts-Mall. It is difficult to talk about high quality, since packaging companies work with different manufacturers, so the box can be of excellent quality or vice versa.

In the case of the oil filter, which changes every 7000-15000 kilometers, it is better to install the original or premium analogues. The cost of the product will pay off, but the savings will lead to costly consequences. 

Installing a new filter

The oil filter is replaced during routine maintenance. Changing it is simple:

• if the filter is case-wise, then with the help of a key it is necessary to tear it off, then unscrew it by hand. For lack of a key, the filter housing can be punched with a screwdriver, then easily unscrew by hand. It is absolutely necessary to add oil to the filter housing to prevent the engine from starting “dry”. The new filter is tightened manually to avoid torn threads;
• filter insert changes easier. The case is usually at the top. Unscrew the plastic cover and take out the used filter element. The case must be wiped with a dry cloth, eliminating dirt and mechanical impurities. Insert the new filter into the seat, put on a new O-ring on the cover. 

How to keep the new filter working?

Initially, you need to purchase a high-quality filter that will fully cope with the responsibilities. If the mileage of your car is more than 100 km, it is recommended that you use a flush during the subsequent oil change, as well as remove the tray for washing and cleaning the intake grid. After that, less dirt will linger on the filter, respectively, its throughput will remain stable. 

When the motor starts cold, especially in winter, do not allow it to work at high speeds, otherwise the filter element will compress under the influence of high pressure.

Hack and predictor Aviator

The oil filter is the most important part of the engine, allowing the oil to work clean. The resource of the power unit and oil consumption depend on it. It is highly recommended to use original components, thereby ensuring the correct operation of the internal combustion engine and oil system.

Questions and answers:

What is the oil filter used for? This is an element of the lubrication system, which ensures the cleaning of oil from burning and metal shavings, which appears as a result of the operation of various mechanisms in the unit.

What filters are used for oil purification? For this, classic full-flow filters with a paper filter element, gravity filters with sedimentation tanks, centrifugal and magnetic are used.

What is an oil filter? This is an element, often in the form of a hollow bulb. A filter element is placed inside it, which ensures the inflow of dirty oil and the output of the cleaned one.