1992 Chevy Silverado oil pressure

-40deg can do a lot of weird things-what is the oil vicosity your using and was the last oil/filter change?

That cold even a 5W20 will cause the oil pump to have a hard time pushing the oil through out the engine-Its just the cold-Do you hear knocking noises when its happening-if so check the oil pressure with a mechanical gauge

Sounds like the oil pressure sending unit is out of calibration-could also be the oil pump sticking-check the oil pressure with a mechanical gauge.

The only way for him to find out is to hook up the gauge and read off

Causes of Low Oil Pressure that will trigger the oil light

Possible causes include:

Excessive main and rod bearing clearances (someone may have installed the wrong-sized bearings or standard-sized bearings on a reground crankshaft). Only 0.001" of extra clearance in the main bearings can reduce oil pressure by up to 20%!

Excessive camshaft bearing clearances (a bearing may have slipped out of place when the cam was installed).

Excessive clearances inside the oil pump.

Leaks between the oil pump and engine.

Oil pump relief valve stuck open or installed backward.

A loose or mispositioned oil pickup tube (too high in the oil pan).

A defective oil pressure sending unit or oil pressure gauge.

Low oil level in the oil pan.

Cracks or leaks in the oil galleries or gallery plugs.

Cracked oil pump housing (improper installation).

Oil viscosity too thin for hot weather.

Oil viscosity too thick for cold weather.