[old_master]

Don't rely on the oil gauge in the dash, they are not known for their accuracy. Rent or buy a manual oil pressure gauge and test it. Something else to consider is if the fuel delivery system has a leak inside the plenum, excess fuel will drain into the oil and thin it out which will cause oil pressure to drop. Usually you'll notice a driveability issue if that happens though. A fuel pressure and leakdown test would confirm if there's a leak. Takes about 10 minutes to run the test, but you'll need a fuel pressure tester and they're available at most auto parts stores for under $40. Harbor Freight has one for under $20, not "professional quality" but it works.