Reduced oil pressure
Low oil pressure can manifest itself in various ways. If the vehicle is equipped with an oil pressure gauge, then the most obvious indication of low pressure will be low readings on that gauge. But before you suspect wear on a lot of engine metal parts, check a few things.
Make sure the oil pressure warning light is working properly. Verify that the problem is indeed low oil pressure by removing the oil pressure switch and installing a mechanical oil pressure gauge in its port. If you do not have such a pressure gauge, then you can rent it in the workshop.
The oil pressure you should expect will change with the oil temperature. The oil temperature will change with engine temperature. It is possible that the engine will be cold when you perform this test. Cold oil, by definition, gives higher pressure than warm oil. This will also be true when using multigrade oils.
With the mechanical oil gauge connected to the port where the oil pressure switch was installed, start the engine. Immediately after starting the engine and before actually checking the oil pressure, check the pressure gauge connection and make sure that there are no oil leaks. Even small leaks on some gauges can cause an error in the gauge reading. If no leaks are found, compare the oil pressure with the values given in the engine data sheet.
This oil sump shows the results of too infrequent engine oil changes. The layer of deposits at the bottom of the pallet has a thickness of 1-1.5 cm.