Can I Use WD40 To Oil Air Filter? (Mechanics advice)

Your atv air filter is critically important, but you already know that. The correct oil is important too though a filter can’t trap

WD40 doesn’t have the correct characteristics to act as an air filer oil substitute. Air filter oil needs to coat the filter evenly and remain sticky, this helps trap dust, dirt and repel moisture.

In this post You’ll learn about an air filter oil alternative, how to oil your filter and cleaning your filter.


WD40 is a fantastic product, I couldn’t run my shop without it. But it won’t be any use as an air filter oil. WD is excellent at cleaning and penetrating but it drys out and won’t help trap much dirt.

And you already know how important keeping your ATV air filter clean is. A dirty filter can cause your engine to feel sluggish and cause black smoke which is a real sign she’s running rich.

A rich running engine is washing the bore with raw gas which will kill the motor eventually.

Running without a proper functioning filter will kill your motor too. Fine dust particles will sand blast the insides of your motor, eating it from the inside.

Engine oil isn’t ideal and I don’t recommend using it long-term, but if your stuck, you can use clean engine oil. Synthetic oil works best as it’s lighter and coats more evenly.

Using engine oil will cause the oil to drip off and pool in the bottom of your air-box. It simply doesn’t have the correct properties for air filter oil.

It will however trap fine dirt and dust particles and help repel moisture in the short term.

But I would recommend getting air filter oil as quick as, because you know running your engine in dusty conditions increases the chances of problems.

Air Filter Oil

Air filter oil is special, it may seem like it’s just oil but it contains additives that make it:

  • Sticky – Which trap even microscopic grit and prevents it from eating your carburettor and valves.
  • Repels moisture – Oil and water don’t mix, they’ll avoid each other when they can.
  • Easy to apply – The oil is thin when applied and so makes the job of evenly coating the filter easy.
  • Fire retardant – A backfiring motor can send flame to the air-box, it’s obviously important the air-filter doesn’t catch fire, but it would make great story.

Some manufacturers have come out with an Eco friendly biodegradable oil, but petroleum and synthetics are available too.

How To Clean Your Filter

Go ahead and remove the filter from the bike. Be careful when removing the filter from the air-box. That’s when crap from the filter can simply drop into the carburettor intake rubber duct.

Examine the mouth of the duct, it shouldn’t be dusty. If it is your filter wasn’t seated properly or is damaged. Check the rest of the ducting for tears.

Go ahead and remove the filter from its cage and and inspect for tears, holes or busted seems. If it’s damaged it useless and not worth cleaning.

To clean the filter, the I use an air filter cleaning solution which does a really good job but does require rinsing and drying afterwards before oiling.

I know lots of guys just use gas to clean their filters and that’s OK, but some filters may split at the seems when soaked in gas.

After a thorough cleaning, wash in detergent and rinse in warm water, allow it to air dry.

Stuff a clean shop rag into the carb duct mouth and using compressed air if possible blow out the air box.

Clean the filter cage, air box and air box lid using some carb cleaner or gas and a clean rag.

Oil The Filter

To oil the filter I keep fresh filter oil in a clean sealed container, I submerge the filter in the oil and work it in by squeezing (not twisting), I allow it to sit for ten minutes and repeat.

The filter now needs to sit and dry until the oil turns sticky 2-3 hours depending on temperatures.

The final step before assembly, apply a ring of regular axle grease or whatever type you have to the sealing ring of the filter. This is guaranteed to stop crap sneaking in under the filter seal.

John Cunningham

John Cunningham is an certified mechanic and writer on I’ve been a mechanic for over twenty years, I use my knowledge and experience to write articles that help fellow gear-heads with all aspects of ATV ownership, from maintenance, repair to troubleshooting.

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