A little tip gleaned from Doktor MB: Do not ever invert the oil cap; when you remove it, place it right side up on a rag or paper towel. Try this method and see if you 'leak' goes away, it worked for me.
If that doesn't work, you can try replacing just the rubber seal (available from Rusty) or the whole cap (likewise) or the entire valve cover (again, but rather $$$!) Very respectfully, /s/ LCDR Meade M. Dillon, USNR Digest Lurker since 2001 '85 300TD 322k miles (Euro 5spd) '96 Infiniti I30 149k miles (wife's 5spd) '73 Balboa 20 'Sanctification' Charleston SC