The answer is a resounding yes! Motor oil is used to lubricate, cool and clean your engine. Certainly for the first two the pressure of the oil has to be at a certain level in order for the oil to do these jobs. Although there is no need to know the exact car oil pressure you do need to know when it falls below a certain level. To this end an oil warning light will come on. Some cars are fitted with an oil pressure gauge to show you the pounds per square inch of pressure in the oil but these tend to be in performance cars or added as customisations by car enthusiasts.
Motor oil lubricated by providing a coating for metal parts to slide over, rather than rubbing against each other directly. If the oil is not under pressure when the moving parts try and come into contact with each other they will encounter no resistance from the oil, resulting in the oil being swept away and the parts rubbing together. But when the oil is pressurised it has a force of its own to counteract that of the moving parts trying to push it aside. In this way the oil is sandwiched and provides lubrication.
Cooling is also a critical part of the oils functions and because it coats much of the metal inside the engine it can absorb heat through this surface area. But pressure is needed to keep the oil circulating so the heat can be extracted from the oil by the airflow under the sump. Pressure keeps the oil moving quickly enough to allow this cooling to take place.
The final job of engine oil is to clean. It does this using detergents and cleaning agents added to the oil when it is made. But these chemicals get used up and motor oil needs replacing because of it. These chemicals are essential to the well-being of the engine and cheap motor oil often doesn’t have them. This is why you should not opt for a cheap oil change but rather always go for premium motor oil. It really is worth the extra few dollars.