If the O.E.M. does not use any type/kind of sealer on the gasket then I do not use any type/kind of sealer when replacing a gasket. There could be some instances where you may need to use some sealer and for instance I had a tiller in the shop where the carburetor air horn and float bowl had so much clearance due to warpage that the owner decided to use sealer instead of spending the money on a new carburetor. This repair lasted and the owner was satisfied knowing that the repair could fail and lead to carburetor replacement so use your best judgement and follow O.E.M. recommendations.