You can use any type of grease (wheel bearing, assyembly lube, ETC) it just takes a light coat around the seal. The silicone on the top & sides of the adaptor plate is also a good idea.

 

Get a different filter or go to a Lowe's or Home depot and ask for some Integrity Subfloor tape. This a 3/16" thick and 1-1/2" wide soft foam tape. It is adhesive on one side. Place the adhesive side against your filter and some from the carb housing leaving the none sticky sides against eachother. Run a bead of lube/grease between the 2 seals to ensure that the sand/dirt stick to the grease. With two layers of foam gasket it will be tight enough not to leak as much as the original K&N set-up.