I run in the 1/10 nitro truck Off Road with a Losi XXX-NT Drake1 with OS .12 CV-R. We just did a track change last week and I was out doing test runs with it. The track was powder dry and I dusted everything pretty good. After getting home I blew the dust off, took the filter off to see how dirty the foam was. After inspecting it closely, no dirt got past the foam but it was pretty nasty. Dropped the foam into an old pill bottle with K&N Filter Cleaner to soak for about 20 minutes. Then washed it out in hot water, squeezed it dry in a towel. Then applied a heavy coat of K&N Filter Oil and squeezed out the excess in a paper towel. Cleaned the Motor Saver and dropped the foam back in and ran it Saturday at the races. No problems at all with it.