Dash01

Car (non-Porsche) gets low oil pressure indication after it warms up, but only with low rpm when coasting to a stop. It has new pressure sender, new 20W-50 oil, and new OEM filter.

Inspection of the oil pan and head show no signs of oil starvation or sludge. The new oil pressure sender acts the same as the old one, i.e., the low oil pressure symptoms are the same as before installing the new sender.

So, why would a low oil pressure indication happen after warmup, but not before?

Airflite40

Sounds like rod bearings are worn, or maybe wrong oil.
As the engine warms up, the oil gets thinner, which is why oil pressure is high when the engine is cold and idling then drops when the engine is warm and idling.

Dave951M

Vehicle? Miles?

Some cars have two oil pressure sending units, one controls the idiot light and the other a gauge.

M758

It is common to see lowish oil pressure at idle after warmed up. At RPM the oil pressure should go back up. Low oil pressure at 3000 RPM is problem.