I have allways used petrol rinse,straight into warm soapy water let it dry,put filter into old shoping bag ,squeese oil through,remove and wrap in newspapper to remove excess oil,grease outside rim where it seats on airbox.
Ps have now gone to turps,grabed the wifes tupper ware tub and a cake rack thingy that fits beautifully in the bottom of the tub and the lid goes back on ready for next time.
(f*$k f*$k f*$k she just read this and stormed out )
DONT USE WIFES TUPPERWARE OR CAKE RACK THINGY.
Hope to talk again toes