Valves in oil filters - find out about their functions and effects

There are three types of valves which can be found in SPIN-ON oil filters. Their use in a given filter depends on the design of the filter, as determined by the engine or vehicle manufacturer. Find out about the functions of individual valves and why they are so important:

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Anti-drainback valve

This valve is most often in the form of a rubber membrane adhering to the inner side of the spin-on filter cover. This membrane obscures the holes through which dirty oil gets into the filter. The purpose of the anti-drainback valve is to prevent the oil from escaping from the filter when the engine is switched off. The anti-drainback valve is required in filters screwed from the side or top of the engine body (if the filter’s cover is facing upward, gravity assumes the function of the valve).

Bypass valve

The bypass valve is used when the filter is clogged due to a long period of time between replacements or when the vehicle is running at a low temperature (when the oil is cold and dense). The bypass valve is opened as a result of the pressure increase in order to increase the throughput of oil flow in the engine as there may be a risk of insufficient lubrication of the parts working together. The use of a bypass valve results from the fact that dirty oil is always better for the engine than its total absence. A lack of oil lubrication can damage the engine.

Anti-syphon valve

This valve prevents the oil from running out of the filter when the engine is switched off. It has a function similar to that of the anti-drainback valve - with the difference that the valve is placed on the "clean side" of the filter. As a result, the filter is constantly filled with oil, regardless of whether the engine is running or not. After starting the engine, the anti-syphon valve significantly reduces dry friction between the parts working together, as it contributes to the rapid flow of oil to the engine.  

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The FILTRON range holds more than 2700 products, and covers 97% of the European passenger-car market. Mechanics appreciate the high quality of the FILTRON-brand filters. Every year, more than 36 million FILTRON filters find their way to mechanics from all the European countries.

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