Foam Filters

I know this is a car forum, but I amuse that some of you have a lawn mower of have used a foam filter. I cannot find a straight answer on what oil to use to oil it after cleaning. Some people say that regular oil that you have sitting around is fine. While others say actual foam filter oil is tacker and will work better.
So, I guess what I’m saying is what oil do you guys use of foam filters (is foam filter oil just a money ploy? What do you use to clean them (a de-greaser? or just Dawn?)? How often do you clean them?

if this is for your lawn mower…don’t worry about it. it doesn’t really matter. use dawn to wash it off and just put it pack on dry or wet. the dirt will be trapped sufficiently with or without oil.

Yes it is for a lawn mower.

Before I switched to an electric mower, I would just use the same 30 weight oil I used in the mower. It worked fine.

On a motor as unrefined as most mowers, it isn’t going to make a difference either way, as long as you make sure you clean it first with dish soap, rinse it thoroughly, and don’t use too much oil.

I use regular 30 weight engine oil. For cleaning I prewash with mineral spirits; wring dry; soap and water rinse; wring out; let dry; oil with a squirt oil can; kneed the oil throughout the foam inside a plastic baggie; and squeeze the excess oil out. Also I wash the housing out with mineral spirits; blow out with air gun; and let dry while I finish the foam filter.

About every fourth or fifth time I just replace the foam and do the oiling as usual.

The special filter oils are for cotton filters used in cars like the K&N filters. The oil is a little toxic so precautions are needed. These filters are the primary filters for the car.

The foam filter used in lawn mowers is a pre-filter so if isn’t 100% effective, then that is OK, the paper filter is the prime filter. The foam filter just extends the life of the paper filter. You can leave it dry but the paper filter will clog up a little faster.

If you are fastidious about this, wash it in any detergent and water, dry out and then use any detergent motor oil. The oil you use in the lawn mower engine will work just fine. Use just a little and squeeze it through the filter with your hands. Its a bit messy. I usually wrap it in a paper towel before squeezing so the paper towel gets a lot of the excessive oil before it gets to my hands.

It is important to squeeze or dry most of the oil out of the foam. Otherwise you will have a mess, it will not pass air easily, and you may suck oil on in to the paper filter or the air intake.

Anything is fine. After washing in solvent and drying, put oil on it (10, 20, 10-30, etc.) and wring it out with paper towels. Any oil will trap the dust.

I would use a little ATF but it’s not critical…

“The foam filter used in lawn mowers is a pre-filter so if isn’t 100% effective, then that is OK, the paper filter is the prime filter.”

No, it isn't.

A foam filter is the only installed filter on the 148cc Briggs Classic/Quattro with the pulsa-jet carb that sits atop the tank. I always clean it with dish soap, then oil it inside a baggie, as previously mentioned. I use motor oil, but if you've got bar-and-chain oil lying around...use it.

I seem to recall 2-stroke Lawn-Boys use foam filters, too.