What Is An Oil Filter And Why Is It Important?

The engine in your Subaru needs clean motor oil to run through it at all times. It's easy to believe that the oil remains clean after being added to the engine because it just circulates through the engine without being exposed to external elements. It's not quite true.

Even though motor oil stays in the engine, it gets dirty really fast. It's because the oil continually picks up combustion byproducts and and tiny metal shavings as it runs through the engine.

Since dirty oil is detrimental to the engine's health, your Subaru needs an oil filter to trap the dirt and debris before sending the oil along to the engine.

What Does an Oil Filter Look Like?

Subaru filter

Subaru oil filter #15208AA130 for 2011 Foresters and 2013-2019 BRZs

Situated between the oil pan and the engine, an oil filter is about the same shape and size as a soup can. It has a few components, including:

  • Metal housing
  • Pleated filter
  • O-ring
  • Bypass valve

An oil filter might be small, but it plays an essential role in ensuring that your engine gets clean oil at all times.

How Does an Oil Filter Work?

As soon as you turn on the engine, the oil pump starts moving oil through the engine. However, the oil sitting in the oil pan doesn't enter the engine until it runs through the oil filter first. When oil enters the filter, the pleats in the filter trap the dirt and debris in the oil. The clean oil moves on to the engine. This process continues in a cycle until you shut off the engine.

An oil filter is designed with a bypass valve. If the filter's too dirty, it can no longer filter the oil. Usually, a dirty filter wouldn't let anything through. However, the bypass valve enables the filter to feed dirty oil to the engine anyway. It's designed like this because, even though dirty oil is detrimental to the engine's health, it's much better to give the engine dirty oil than no oil at all.

What Happens When You Don't Change the Oil Filter

Filter change

Oil filters need to be changed every time you change the oil in your car. If you neglect to change the oil filter along with the oil, the filter will get clogged up before the next oil change. Then the bypass valve will open, and let the oil pass through to the engine without filtering it at all. Dirty oil causes engine components to wear out faster than they should. For example, worn piston rings and cylinder walls will eventually result in the engine burning oil. There is no inexpensive way to fix this problem.

The good news is that you can get a high quality genuine OEM Subaru oil filter at wholesale pricing online from us. Look up your Subaru model in our catalog to see if we have an oil filter for your car!