Scott is correct, see following from MMH_912 Series_ED3_M2 (Sept 2012):
Checking air filter
General note
BRP-Powertrain
MAINTENANCE MANUAL
In the event of dust formation, clean air filter at correspondingly shorter intervals. If filter mat is damaged, replace air filter.
A dirty filter insert will not only reduce the engine performance but might also promote premature wear of the engine.
Carry out visual inspection of air filter after prescribed maintenance inter- val. Clean dirty air filter as described in aircraft manufacturers Maintenance Manual.
2.1) General note
Cleaning
Cleaning the air filter
Never use gasoline, steam, caustic liquids, strong detergents, particle cleaning agents or high pressure cleaners during this step.
Do not dry over naked flame, with compressed air or with hot air gun.
To clean the air filter the following steps are necessary: See Fig. 1 and Fig. 2.
NOTES:
The procedure for cleaning air filter applies to the K&N style filter supplied by ROTAX (BRP-Powertrain) but may vary for filters used by aircraft manufacturer.
Step
Procedure
1
Lightly tap and brush off surface dirt (A).
2
Spray K&N filter cleaner onto filter surface and leave to soak for approx. 10 min. (B).
3
Rinse air filter with low pressure water from inside to outside and let element dry naturally (C).. (Bold Mine)
After cleaning
Fig. 1 08525
Never use gear oil, diesel or engine oil, as they attract humidity.
NOTES: Each filter pleat must be sprayed with oil.
After 5 to 10 min. the filter will be soaked with oil, noticeable by the uniform red coloring.. (Bold Mine)