Can I rub some 10/40 into it or would that be ridiculous…?
Do I need to buy a can of sprat specifically for it?
Cheeeeeeeeeeeeers
What filter? You don’t normally need to oil filters, if it’s K&N buy K&N oil (I’ve got some if you want to use a bit)
It’s the stock filter from the 636. It’s in pretty good nick, I gave it a good clean and it seems fine. Not sure if I can justify spending £40 on a K&N…
It was oiled when I took it out and the workshop manual says to oil it… Might take you up on the offer Alex if I don’t find any other stuff! 
Strange, in my manual it says throw it away or just blow it out with compressed air.
K&N oil is there whenever you like though.
wrong oiling will decrease air flow, get this for 10 pounds 
Depends on the bike I guess, my GPz suggests SAE 30