Oh yeah, this is 2.0 L 8 valve engine / automatic tranny

So the only thing that will make the oil light flash and beep is low oil pressure?

In the past 6 months I've put a new oil pan gasket on it, intake gaskets, valve cover gasket, crank, cam and intermediat shaft seals, and maybe a couple of other gaskets . . . basically, every seal and gasket except the rear main.  On some of the paper gaskets I used a tiny bit of high temp silicone that I rubbed into the gasket . . . not enough to squeeze out a bead anywhere.  All the seals and gaskets I've put on were supposed to be OEM parts (according to autohausaz.com where I bought them).  The car did spend 10 years in the rust belt (Penn and NJ) but it only had 75,000 miles on it when we bought it . . . and I saw the car facts report to support that it was the correct milage.  It has 80 something K on it now.  There was no sign of sludge under the valve cover or in the oil pan when I had them off and I didn't use any silicone on the pan gasket.

I'm 99.99999% certian that it's something related to the last oil leak I fixed (oil cooler O-ring and flange gasket, oil sending unit).  It has never done this before and it did it the first time I drove it after repairing the leak.  I changed the oil and filter while I was at it . . . Castrol 10W40 oil and a Bosch filter.  Oil level is right on the full mark.

Think the filter may be the problem?  Could it be a bad sending unit?

Was the oil pressure switch that you installed the same color as the old one?  The different colored switches will set the oil pressure warning off at different pressures.

Besides the unfinished silver/whitish metal, I didn't notice any color . . . but I wasn't really looking.  Would the whole thing be a different color or would it be marked somewhere on it (like the top or the threads)?

I'll change the filter and see what happens.  If that doesn't help, I'll go back to 20W50.  If that doesn't help, I'll get another sending unit.

If that doesn't fix it, I'll take it over to Smelly Cat's place and see if I can borrow a switch out of an old kenmore to rig it up to bypass the sending unit when I'm accellerating.   :wink:

Rick,  Correct me if I'm wrong,  but wasn't there also a little printed board behind the dash that control some the functions of the oil pressure switches/ buzzer. It seems to me that I had to replace a lot of those boards.

10-4 on the different bar values, so if you use the wrong one, it will keep setting of the oil buzzer even if nothing is really wrong.
 These cars have sealed clusters, you can only replace the bulbs, they don't use the old style external printed circuit boards like you had on the gti...

Yeah... the newer clusters you can't even replace a bulb in. I had a tt yesterday that needed a new cluster....$829.00.... :shock:
An old air-cooled car looks better every day.

Zen, unless you're engine is clattering like an old diesel I'd say that the engine is making enough oil pressure to keep the switches happy.  On your car, there's 2 different oil pressure switches - one on the cylinder head and one on the oil filter housing.  The one on the cylinder head can be either brown or blue - the brown one activates at .3 bar  (4.4 psi) and the blue one at .25 bar (3.6 psi).  The switch on the filter housing should be white - it activates at 1.8 bar (26 psi).

Make sure that you don't have the switch for the head installed on the filter housing or vice-versa.  I've seen that done before and it causes all sorts of "fun" before you figure it out.

BTW, VW calls this it's "Dynamic Oil Pressure Warning System".  Check out this link, it's got a pretty easy method of how to check the system.

http://reflectionsandshadows.com/cabby/dopws.html

Have fun