I have a 2002 90hp mercury 2 stroke and used the quicksilver oil that came with the motor. This spring I tried Pennsoil synthetic, I noticed that the oil tank level dropped much faster than the regular quicksilver oil did (about twice as fast. No problem with fouling plugs and motor runs great. Does the synthetic just burn faster? Is this a good thing or should I return to using the quickslver? If the synthetic is used faster it makes it even more costly to use.