96 Tacoma, oil leak? gook?

I bought this 96 Tacoma about 6mths ago. It has about 72k miles on
it, and was checked by my mechanic. About 3 weeks after I bought it,
I changed the oil. I noticed a thick gook around the oil cap, and
surrounding area. I cleaned this up, and changed the oil About 1
week after this, I checked the oil, and nothing was on the stick! The
area where I park the truck didnt have oil under it. I also looks
under the engine and didnt see anywhere the oil could be leaking. I
then added some more oil, and it seemed fine. I checked the oil again
a couple of days later, and a little over low was shown. I decided to
leave it the way it is, and check it the next day. I checked it, and
it was almost full. I decided to leave it be. Today I checked it,
and nothing was shown.

Could that gook I noticed earlier be causing this? Maybe the line
where the stick goes is clogged? What causes this gook? What can I
do to clean the oil resouivor out?

Any tips/suggestions welcome. Thanks.