After picking up your car from service, you may notice that your vehicle’s oil filter was replaced. What does that mean, and why is it important?

Back to Basics: What is a Oil Filter?
The Inside of an Oil Filter

Why do you need an oil filter?

In order to keep an engine running effectively, motor oil is constantly being circulated through the vehicle’s engine. As motor oil moves through various parts of the engine, the motor oil picks up dirt, grit, and even metal shavings. As contaminants get trapped or kept in suspension, the oil may thicken, forcing the engine to work harder to maintain quality performance. Over time this can impact fuel economy and puts unnecessary wear and tear on your engine. Although certain motor oils such as Pennzoil Ultra Platinum are proven to keep pistons and other engine components 50% cleaner than the industry standard1, your engine still needs an extra level of defense against contaminant build up within the motor oil. This is when an oil filter gets to work.

Back to Basics: What is an Oil Filter?
Pennzoil Ultra Platinum Full Synthetic

How Does an Oil Filter Work?

Motor oil resides in the oil pan while at rest or have a very short rest window in the pan while in operation. Before it circulates back through the engine, an oil pump pulls the motor oil up, and sends it through the oil filter. As the motor oil flows through the filter, it travels through pleated folds, or media, and impurities such as dirt, sludge and large particles are filtered out before it is sent back into the engine for use.

Like motor oil, oil filter also has a limited filter life. Over time, the filter will get to a point that it will not be able to trap anymore impurities and pressure will build up because it is clogged full of contaminants. This increase in pressure will open the bypass valve within the filter to allow oil to continue to flow and circulate in the engine; unfiltered and to prevent oil starvation to the engine. To keep your engine performing at its best, it is recommended to change your oil regularly and replace your oil filter at the same time.

Pennzoil Platinum HE oil filters are engineered with an exclusive synthetic-blended 2-ply gradient density filter media designed to remove up to 99%2 of motor oil impurities while trapping on average over 10 grams of contaminants based on industry tests3. This provides an average 15% greater cleaning ability, and over 3 times the dirt-holding capacity of economy oil filters. Once the motor oil passes through the media, it drains through the central hole and back into the engine.

Back to Basics: What is an Oil Filter?
Pennzoil Platinum HE Oil Filter

What Oil Filter Is Best for Me?

Small variations in design mean that each vehicle, and therefore oil filter, is unique. Whether you are changing your own oil, or you’re bringing your vehicle to a mechanic, be sure to use our oil filter finder to determine the best fit for your vehicle.


1 Based on ILSAC GF-5, Sequence IIIG piston deposit test using SAE 5W-30, and Ford, Chrysler and GM specifications. Does not apply to Pennzoil Platinum® Euro products.
2 Based on ISO 4849-12 test procedures.
3 Based on ISO 4849-12 test procedures.