Blow-by inhibits performance
because it results in a loss of compression. When the expanding gases slip
past the rings they cannot as effectively push the piston down and make
the vehicle go. As a result the car will have less horsepower. This also
results in a loss of fuel economy.
When the fuel, air and moisture slip
into the crankcase they contaminate and dilute the oil in the crankcase.
Among the many gasses in your compression
chamber are unburned fuel, moisture, sulfur dioxide and soot. Once these
gasses slip into your crankcase they can dilute into your engine causing
great damage.