2001 Grand cherokee 4.7 low oil pressure in cold weather.

Wrong oil; bad bypass relief valve; bad gauge.

b2600???? is that a MAZDA? oops.....a .....daisy......
what car? jeep>? you posted to jeep. if not a jeep go to correct forum.
what engine, there are many.
is this an engine part or tranny, both have pumps. and relief valves.
just a clue here.

Oil pump should have a pressure relief valve but hard to know since you're keeping the year, make, model, engine a secret.

Normal oil pressure should be between 40 and 60 psi. A cold engine will normally have higher pressure. If you're seeing 75 psi on a warm engine I would recommend having the pressure checked with a manual gauge to verify the gauge in the Jeep is working correctly. If the gauge is correct oil viscosity may be too high (oil too thick) or there may be a problem with the oil pump pressure relief valve. If the gauge is not correct the sending unit may be at fault.

u have low oil pressure, the oil pump has a stuck pressure relief valve, DO NOT DRIVE THIS CAR until this is fixed, u will burn up a $3500.00 engine

its probably the sender. there is no good way to test them without a mountain of tools. its easier to replace the sender i think its pretty cheap

it could be the sensor you should look at the oil pressure relief valve

Try replacing the oil pressure sending unit.

If cleaning the engine does not work, replace the oil press. sending unit. These senders on Jeeps have had a history of problems where they will work one day and not the next day.

i hate to sat it but you could need a new oil pump. hope this helps you.