Motor seems good from what I can tell. Yesterday's 180 mile trip gave 24mpg @ 75 mph average speed. At 62-65 mph I get closer to 30mpg so that part seems fine. Also, oil consumption is very low, about 1 qt. every 1500 miles so I assume the motor is good but the oil pressure worries me a little.

On start up it rises as it should to 45. Driving it maintains that pressure after any extended driving on the freeway that pressure will drop to about 18 at normal idle while in gear, though rise shortly later to around 25 on the gauge.

Is this acceptable or should I be concerned? Any input appreciated.

Normal.

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Yes, it is normal for the oil pressure to drop at idle once the engine is good and hot. A lot depends on the weight of the oil you're using and the idle speed, but typically it is normal to see the needle to drop about halfway down at idle.

Despite what the manual says I have never seen one ever come close to .3 bar (5 PSI) at idle and that would scare me. 15-30 PSI (1-2 bar) is more typical and unless yours was below 15 PSI I would not worry about it at all.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

It's always stayed well above 15 but I seem to recall about 20 years back when I had my first Mercedes [240D] I read the pressure wasn't supposed to drop below 32, and if it fell below 30 it could be reason for concern.

Either the specs are different now or what I read then was wrong but I don't recall that car ever having the oil pressure fall below 30.