Twin Webers on mine DCNF down draughts . I remove them at the start of the season and soak them in a tray of white spirit ( NOT TURPS ) . Let them evaporate dry . K&N do an air filter oil ( its pink ) 8fl onz give them a coating ( instrutions on the bottle ) , you will get a bit over spray on the bonnet after your job, but it wipes off and no damage from it . Do the same when you put it away at the end of summer . OH I forgot its OZ no winter over there .

Just had my b/fast 10.30am now I can think I need a mug of coffee to help.
Details from the plastic bottle
If your K&N High Flow Performance Air Filter is white ( not red ) inside the pleats, it must be oiled before installation and after each cleaning . It's easy heres how.
Gently squeeze a small stream of K&N Oil along the leanght of each pleat on your filter(CAUTION )use restraint...and its easy to get to much on the filter )
After oiling, let flter sit for 20 minutes so the oil can dissipate throughout the gauze, resulting in a uniform light red color
Do not over-oil . Any white patches remaining after 20 minutes may be finished off with a drop or two of oil.
Your K&N Filter will provide efficent , high flow service for extended periods and will not require cleaning until completely covered with a thick layer of dirt. ( I dont get mine like that .
Sort out the bones in this lot and it should help you owe me a beer and a burger mate and not that Fosters crap.
Off for more coffee