Modern Vespa

Is it a big deal?

I personally prefer the spray on air filter oil. After cleaning I lay the filter on a clean rag, spray on an even coat over the inlet side of the filter and then lay another clean rag on top and blot the excess. YMMV

I used the k&n spray that i found. It was an old filter care service kit that came with and air filter cleaner. i sprayed the outside of the filter after i cleaned it. but not sure if i should have used petrol and maybe 10w30.

filter sprays are typically a bit stickier than engine oil and will help in catching finer dust particles. Either way is fine though. The biggest thing is to not over oil it and to let it fully dry /tack up before reinstalling.

Alot of folks have 2 filters. This way they can have one clean and prepped ready to install that is stored in a ziplock baggie. Then when servicing they just swap it out. Clean the dirty one when time permits and re bag it.