Scary (engine?) Noise!

Got this terrible freakin scary noise from the Passat engine
compartment. Stopped and lifted the bonnet. It sounded as though it
was coming from the engine rocker cover area so I took off the oil
filler cap and saw oil splattering about; checked the oil level and
there was certainly oil there. Felt the alternator and it seemed OK
although the noise did *I THINK* settle down if I held the alternator
bracket - not really sure. The noise did NOT seem to increase as I
revved the engine - strange. On the way home, for no apparent reason-
the noise disappeared and the car drove fine. There was no hint of
anything when I drove it the day before and I covered about 70
miles. At home I checked/ tightened the alternator bolts and they
seemed OK. SPOOKY! I have not had the need to drive it today.

Any ideas what it could be so I can tackle it BEFORE it either gets
worse or breaks down?

What kind of a noise was it??? a squeel? a banging? a ticking?

One thing I've learned about the 92 passat, it makes noise. Mine is always making SOME form of scary noise. Your best bet is to just ignore it until something breaks. Otherwise you probably arn't gonna figure it out LOL. Either way I wish you the best of luck with your problems.