I pulled my #4 spark plug wire from the plug, and there's oil all over the boot. I can also see some oil in the hole where the spark plug is. The #1 spark plug wire is also the same way; #2 and #3 are dry.

Any ideas anyone? Is the problem the valve cover gasket?

Vehicle: 1996 NISSAN SENTRA GXE

 

to me it sounds like your valve cover gasket is leaking around the spark plug holes on the valve cover, its an easy fix just dont overtighten the valver cover bolts cause the bolts can break or if you have a plastic vavle cover it could crack. it would only cost a half hour of labor and part cost at a local shop so its not that exspensive if you choose to bring it to a shop.