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Why There Is Much More to a Typical Oil Filter Than Meets the Eye

by Emilia Latvala

When you think about the oil filter fitted to your vehicle, you may feel that it is a straightforward device and has just one role to play. Yet you will be surprised to learn that this part is quite technologically advanced and is not simply a device to catch contaminants. What should you know about your oil filter, and why should you make sure it is always in tiptop condition?

Challenging Scenario

The primary job of the oil filter is, indeed, to protect the engine and reduce contamination where at all possible. After all, as the motor runs at high speed, a certain amount of friction is inevitable, even with careful engineering and advanced lubrication. In this case, microscopic pieces of metal can flake away from moving parts and will then be held in suspension by the oil. As the lubricant is pumped around the engine, it will eventually arrive at the filter, and, in an ideal world, all contaminants will then be trapped.

Ever Present Threat

Of course, the filter will not trap every particle and, when the engine is switched off, the oil (complete with contamination) will sink down into the sump at the very bottom of the block. When the driver restarts the engine, some of this dirty oil will begin to recirculate and could eventually lead to damage. This is why engineers do their best to design the filtration system so that it can cope with all of these eventualities and provide the best protection possible.

Filter Design

Many filters are "full flow" and are equipped with a bypass valve that will activate when the engine is cold. As it's important to lubricate a cold engine as quickly as possible to avoid the risk of damage, this valve will send all of the oil from the sump directly to the engine without sending it through the filter first.

Achieving the Compromise

Clearly, this type of system represents a compromise. While there may be dirty oil in a cold sump, it is still important to lubricate dry moving parts as quickly as possible. Thus the challenge for an engineer is to make the filter as efficient as possible and program the bypass valve so that it is active for a minimum amount of time.

Sophistication Inside

To help them achieve their goal, engineers use sophisticated technology inside the filter. The type of media used to trap tiny particles must have a very high holding capacity while giving the least amount of resistance to the oil flow. In so doing, the filter will provide the lowest amount of pressure loss during a cold start, keeping the oil clean for as long as possible without needing to resort to a bypass valve.

Doing Your Part

As you can see, oil filters are much more than simple workhorses. So, ensure that you take your vehicle to a mechanic as and when requested, so they can inspect and replace the filter when needed.

If you need an auto servicing appointment, including a BMW servicing appointment, Reach out to an auto shop in your area.