payup,
it could be coming from one or more areas. Most likely...
Valve cover gasket
Valve cover bolt groomet(s)
Did your friend tell you which cylinder bank he saw it on (the one close to the radiator or the one close to the firewall)? See if he can point it out to you. Go get yourself a can of engine degreaser (follow the directions on the can), cost about $2. Spray that area, hose it off. You may have to do this 3 or so times to get it nice and clean. Drive the car around for about 5 or ten miles, expressway is best (higher pressure). Then check it again to see if you see it leaking there again. Valve cover gaskets are not too expensive ($15 each), grommets are $20 for the entire set (enough for all of the bolts, on both valve covers).
There is always a slight possibility that it could be leaking from the intake manifold and flowing to that point where your friend saw it, but you'll be able to see the trail once you clean the area, just use a good light, and snoop around.
BOL