What Type of Oil is Best for a Foam Air Filter?

Many dirt bikes and ATVs use a foam air filter instead of a paper or fabric filter. That’s because in offroad settings, there’s much more dirt that can get sucked into an air intake than on the street. 

Keeping that foam air filter clean and properly maintained is a key to good performance, and that means cleaning and oiling the air filter. 

Types of Foam Filter Oils

Generally, there are two types of oils available for a foam air filter. There are petroleum-based oils, and synthetic or plant-based oils. So which is better?

Petroleum-Based Foam Filter Oil

The most widely available air filter oil may not be the best choice, but it’ll work in a pinch. Before synthetic and plant-based products became popular, a lot of riders just soaked their filter in petroleum-based oil, wrung it out a little bit and installed it. But it doesn’t penetrate the foam very well, and that can lead to oil pooling in the bottom of the air box or getting sucked through the intake.

Synthetic and Plant-Based Foam Filter Oil

These types of foam air filter oil offer a much better solution than petroleum-based products. They handle harsh temperatures and adverse conditions better, and penetrate the air filter better than petroleum products. They’re also removed from the air filter easily when you clean it, so it’s easier to get the filter thoroughly cleaned and re-oiled properly.

Do You Have to Oil a Foam Air Filter?

As always, follow the manufacturer’s recommendations for your machine and reusable air filter, which generally includes oiling the filter after cleaning it. A clean, well-oiled filter allows for the best airflow and the most efficiency at capturing dirt. However, some testing shows that not oiling an air filter also works, and even that an air filter doesn’t perform as well right after a cleaning and oiling as it does a couple of rides later.

How to Clean a Foam Air Filter

Cleaning a foam air filter involves using a cleaning agent, rinsing the filter, letting it dry, and then reapplying filter oil. However, the type of oil affects the cleaner you use. If you’re using petroleum oil on the filter, it’ll need to be cleaned with soap and water or a detergent. But if you’re using a synthetic or plant-based oil, the cleaning will go much easier and not require any heavy duty detergent. Once the filter is clean, apply the oil evenly.  

There are plenty of good foam filter cleaners and oils on the market. But keep in mind that the oil that should be used on a foam air filter and the oil for a fabric air filter are not the same, and therefore not interchangeable. Make sure you choose the correct oil for your machine’s air filter. 

What Not to Use

One thing to avoid using on a foam air filter is gasoline. Sure, it’ll cut through dirt and grime on the air filter, but it’ll also cut through the rubber seals and the glue that holds the filter together. Gasoline also degrades the filter, so avoid using it altogether and stick to designated foam filter oils.