I have a 1998 s70 GLT with 190K miles and change the oil regularly. I runs great, until huge snow we had here.
While driving through 6 inch snow my oil light came on, stopped the car and checked the oil level and oil in the camshaft area. Oil was flowing thought the camshaft area and flinging out of the oil filler hole when i reved it up. I figured the pressure switch connector had come disconnected in the snow. I continued to drive the car for day. The light was come on and off occassionally.
In the morning i noticed it took longer for the oill light to go off and could hear the valves in the car but by the time i got out to check the noise it goes away. I decided to let the car warm up a bit longer as the temp here was at 0 degree for days. Today the light came on and didn't go off. By the time i got to my destination i could start hearing the valve noise again.

Do Oil Pumps go bad intermittenly?

Until i can find out the problem the V sits.

 

see the write-up on the front page about oil pan o-ring replacement by tech. The symptoms you describe match fairly well with that. Also sounds like its time for a pcv service.

 

How is the oil level? Is there any oil leak? Can you find any loose wires?

 

The oil level is good, oil pressure sending connection is good, When i bought the car 6 or 8 months ago, i cut the crank case ventilator and ran a hose down to open atmosphere and all was good until this snow and extreme cold. I pulled the oil cooler line and turned the motor over, I had oil go every where in about 2 seconds of turning the motor over. i bet i lost 2 quarts of oil.
I refilled the crankcase and still no oil to the valve/cam area.

 

Okay, first step: fix the PCV system properly. THAT is ONE system you don't want to jerry- rig on these cars. Get all new components: hoses, oil trap, etc, make sure to clean out block ports, and replace. Then... Replace the oil pan o- rings. You have the classic sign of those being cracked or otherwise compromised, namely, low oil pressure, especially during cold weather. There's a write- up at the top of the thread on this.