YOU MORE THAN LIKELY HAVE A BLOWN PLENUM, CAUSING OIL TO BE SUCKED INTO YOUR #6 CYLINDER! IT WILL CAUSE ROUGH RUNNING, FOULED SPARK PLUGS AND OIL TO BURN CAUSING YOU TO FAIL AN EMISSIONS TEST! Think he heard me?

 

If you've read the plenum sticky by now then you have good idea what's going on. Simply replacing the gasket probably won't fix the problems resulting from driving around with it blown. Ask your mechanic to do a leak down test on that cylinder or find one that can. If your plenum gasket is blown then your cat is shot and you may or may not have a burnt valve. Take all that into account to figure what it's going to cost to repair. Pass the valium please.