cleaing cone air filter

If its K&N then get some K&N filter cleaner from Halfords - I used it on mine after about 20k miles and has made a noticeable difference aswell as making it look like new agen :-)

oil it afterwards as well put the cleaner in a pan roll the filter in it clean it out properly let it dry spray oil on it refit it

If it is a good cotton one, then you can clean/re-oil them with a cleaner/oil from the same brand (or just use K&N cleaner and oil). Some cones are paper and mesh though and more for image than effect don't know if they are cleable.

Some foam filters can be cleaned but re-oiling can clog them.