'83 240D oil pressure question

[phil2810]

Recently (as the weather has gotten colder in Southern Virginia), I've noticed my oil pressure indication doesn't begin to register for around 20 seconds after she starts, then slowly climbs to "3". It may have alays been this way after an overnight cool down, but I didn't notice it. I frequently (every 150 miles or less) check the oil, so I know she's not low.

I do notice more engine noise before the oil pressure goes up to "3", and it sounds like it's coming from the upper cylinder head (camshaft/valves area). Once the pressure is up, it stays up, maybe dropping to 2.5 at idle, in gear (auto) after she's hot. If I put her in Park or Nuetral, it goes back to 3, even when hot.

Is there a "normal" time for pressure to come up, and if so, what might cause my symptoms of pressure lag. I use standard 15w40, whatever brand is on sale.....


Thanks,
Phil