Engine oil is kept in the engine oil pan on most engines, and an external oil reservoir on many high performance engines. In either case, the oil pump is responsible for pumping oil into the engine faster than the engine can use the oil. This creates a constant pressure as the oil is pushed through oil passages. The oil passages use targeted outlets to send oil to precise locations which need protection. Oil is less of a lubricant, and more of a barrier, as it prevents metal contact between internal engine components. When that barrier is weak, metal contact will occur at an increasing rate, relative to the rate of oil pressure degradation. The barrier the oil creates is weakened or completely compromised without oil pressure. Oil pressure forces oil into the tight areas as fast as the oil is used. This means, when the oil pump fails, engine components will run out of oil, and damage will occur.