If it is a naturally aspirated model crankcase ventilation is through what is known as a flame trap, which is nothing more than a plastic screen attached to the rear of the throttle body. Either the plastic screen or the hose from the crankcase gets clogged, resulting in excessive crankcase pressure. It is very easy to clean this yourself or replace with a new one (inexpensive). I would not recommend any type of stop leak product. My concern would be that it would cause more damage than it is curing by potentially clogging oil passages, etc. Question- Did you recently change to synthetic oil. Some folks have reported seal leaks after changing to synthetic due to the more uniform synthetic molecules getting past an otherwise weak seal.