I have driven a 300CE about 4000 miles since I bought it from my father, the car has about 335,000 miles on it.....I noticed two days ago that my oil pressure gauge has been showing lower pressure every day.....

On start up (engine cold) I read 3 bar, after warming up to 80 C at idle the gauges bumps off of the low needle and reports 1.5 to 2.0 bar at highway speeds.

I pulled the sender cable off of the unit with the key in Position 2 and the gauge reads solid 3 bar, so it is not a bad gauge...I am going to put a manual gauge on engine tonight to confirm oil pressure.

Are there any other diagnostics I can run...

TIA