油压是在大多数内燃机的寿命的重要因素。使用强制润滑系统（由Frederick兰彻斯特发明的），油被一个正排量油泵抽出，被迫通过回油孔（信道）进入轴承，如主轴承，大的端部和凸轮轴轴承或平衡轴轴承。其它组分如凸轮凸角和汽缸壁由油喷射润滑。

足够的油压保证的旋转轴（轴颈）金属与轴瓦不会接触，因此磨损仅限于初始启动和关闭。油压力结合轴的旋转，同时液压集中在其外壳的并冷却轴承。这种轴承被称为一个流体轴承。

当发动机因为油的黏度而增加时，油压力会升高，同时发动机的转速也会增加，直到安全阀打开油泵转移过剩的流动。油压低于热怠速条件和制造商所允许的最小压力，通常在此点给出。过多的油压力可能表明过滤器堵塞、堵塞油道或错级油。低油压指示轴承的磨损或油泵的损坏。

Oil pressure is an important factor in the longevity of most internal combustion engines. With a forced lubrication system (invented by Frederick Lanchester), oil is picked up by a positive displacement oil pump and forced through oil galleries (passageways) into bearings, such as the main bearings, big end bearings and camshaft bearings or balance shaft bearings. Other components such as cam lobes and cylinder walls are lubricated by oil jets.