My oil pressure at idle (transmission in drive, sitting at a stoplight) has always been around "2" on the gauge, or a little bit below. The past few days I've noticed that the gauge is staying high. Sometimes it stays pegged at "3" sometimes it falls to about 2.5. It falls to zero when the engine's off, and is always at 3 with the accelerator pressed. Oil level is normal (halfway between the two sets of notches on the dipstick).

I'm not sure if I'm imagining things but it seems as if the engine might be a little bit "quieter" than usual, although I can't say the character of the noise has changed. Starting, acceleration and smoke level are as usual.

Motor oil is 15W40 Rotella dino, no additives. It was changed in April or May and I've only got 2,000 miles on it since then. Filter was changed at the same time, it's a Turkish-made Fram.

1. What can cause this? Is there some kind of additional strainer or something somewhere?
2. Is this cause for not driving the vehicle? Low pressure would scare me off driving it but I'm not sure what to make of high pressure at idle. My other car's in the shop right now so this is my only set of wheels.

__________________
1982 240D automatic
Odometer quit at 307K...about 325K now