I need help with an oil leak on my 2007 supercharged grand prix

I drive this car primarily on the road with  my job.
it has developed a sudden oil leak. it has 150k  
hwy driven miles under 80mph. I change my own
oil and have never had any issue. It appears to be
coming from the front crank seal area as the oil
sending unit and filter are dry. the motor mount
and underside of passenger side is soaked. I
sprayed entire area with brakleen and laid
underneath running car for about 30 minutes
waiting for leak to reappear. all I noticed was area
of oil pan underneath mount shows oil again. with
size of balancer and pulley I cannot see if its the
crankseal or not. the engine dont appear to leak
from the intake either. the belts are also dry   i am
stumped on what the problem may be  can u help
it loses a quart about every 500 hwy miles