I had the same problem with my 99 f-150. Turned out to be a sick-sensor problem. Replacment of the oil pressure sensor was the fix.
30, cold
The question is nowehere near specific enough to answer.
Especially if you are in cold areas, it takes more pressure to circulate cold oil. When it warms up, the oil flows easier through the system reducing pressure.
some possibilities are. low coolant level, open thermostat, pluged heater core,
Tire maintenance is best done when cold it is the closest to the actual pressure as air warms the pressure rises it may be as much as 10 pounds difference in cars so..... filling a tire warm will result in lower than safe operation pressure when cold.
I would start by replacing the oil pressure sending unit. If that does not correct the problem, I would look closely at the gage itself. If you hear any valve train noise at cold startup, you need to have an oil pressure test run to make sure you actually have good oil pressure when starting the engine cold. Possibly the gage is correct and you do have 0 oil pressure when cold.
Low coolant? Defective thermostat? Heat control cable not adjusted properly? Heater core plugged or airbound?
Often a knock when cold is caused by piston slap, which is pistons rocking in the cylinders until they expand in size when the engine warms up.
The most common cause of this failure is a broken blend door. Check heatertreater.net for diagnostic information and an inexpensive fix.
You will need to remove your oil pressure sending unit and install a mechanical gauge to get a true reading. You need to start out cold and write down the pressure reading and also once it warms up to operating temperature. If the pressure gauge is not the same as the mechanical one you have a bad pressure switch.
It warms their hand when in its cold outside.
It keeps it warms for the cold