Why is Oil Pressurised?
Oil is circulated around the engine by the oil pump. When a liquid is forced (in this case pumped) through a confined area is becomes pressured. Because oil travels inside the engine through bore holes and other cavities it creates a pressure of its own, as measured by the oil pressure gauge. This is called a forced lubrication system and was invented by an English engineer called Frederick Lanchester.
The primary job of oil is to stop moving components from coming into contact with each other. Such contact would be extremely detrimental to the condition of the parts if it were allowed to happen while the engine was running. As it stands these parts only come into contact with each other when the engine is first started. To lubricate oil needs to form cushion between these components, to provide a surface for them to glide over. By preventing direct contact wear and tear is reduced and so is friction. This in turn increases efficiency and reduced the heat generated. But for this to happen the oil has to be pressurised. If it were not pressurised the oil would simply be swept away by the moving parts and could provide not resistance to the forces trying to bring these parts together.
One of the things that can cause the oil pressure to fall is if the volume of oil is decreased. This normally indicates a leak but the level of oil will fall over time through natural wastage. The other way of oil pressure is decreased is if the area inside the engine increases, meaning you have the same level of fluid trying to fill a large area, therefore the pressure falls. This comes about as a result of wear and tear on the engine.
Oil is such a critical part of your engine it is worth learning as much about it as you can, visit the oil pressure gauge guide blog for more information.
