The internal combustion engine  contain numerous fictional part the friction causes them to overheat to reduce friction and remove heat car used a lubrication system this system delivered lubricants to all friction part the most viral part are fact with lubricant under pressure the other part are relay on  gravity and splash feeds
Working :

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We examine whole engine lubricating cycle fill up engine with motor oil is drained into oil sump along the available roots in this case it happens timing drive cavity and the deliciated channels the oil is stored in oil sump that has oil dipstick attached to it oil pick up in oil strainer when we starting engine it activated the oil pump which drowse oil and creating pressure at the outlet in this example the pump is operated by change drive from the crank shaft the pressure relief valve control the lubricating pressure and open when the safe miserable pressure is exceeded it is mounted on either on oil pump
Let’s look how oil pump work
You can see several gear pump act as oil pump they can featured by either internal and external gear mashing in external gear pump there is a crescent partition, gerotor pump and oil crescent partition another variety is variable dischargable oil pump
The pressure oil goes into oil pump in the cylinder oil blocks in the gallery having been cleaned a  wine metal dust and oil impurities by passing into an oil filter if the filter become to clock the oil will pass through the bypass valve without being clampsed so replace the filter everytime you change your oil
The filter outlet are featured with oil pressuring sensor
The oil run along the cylinder block oil gallery to the crank shaft main journals which lubricates the main journals under pressure this produces an oil coating that minimises friction the oil flows in the crank shaft channels which lubricates the rod journals in its connecting rod bearings let’s make a closer look at oil crank shaft pessage the presurized oil is pushed out in the connecting rod bearings the rotation of crank shaft spread all over crank case lubricating the cylinder wall piston piston things and partially the timing drive this also generate an oil mist in the crank case the splash oil thus run out in the oil sump simultaneously some oil flows through the oil gallery in cylinder block the cylinder have eventually reaching the camshaft journals they pushed out the lubricating timing drive by gravity and splash feeds the oil then returned into oil sump and cycle start all over again
The system should contain at least one oil pressure sensor which control system functioning pressure sensor can be placed in the different part of the system including downstream of the filter   and the forehead of oil gallery and sometimes this  is featured with several sensors e.g upstream and downstream of the filter when the oil pressure in the lubricating system is low the warning light in filter iliminates on the dashboard more complex system may include oil temperature sensor, oil level sensors and air water cooled radiators cooling a radiator is also  featured with  various coupling scheme there is also approach to lubrication and cooling of piston, and piston tanks such as extra oil pessage in connecting rods oil holes at bottom of connecting rods and oil jet nozzles in the cylinders block
Lubrication is also required for optional system such as turbocharger some control function can be performed by the lubrication systems thus pressurise the motor oil is essential for the hydraulic lash adjusters some variable valve timing drive hydraulic tensioner
To prevent any access oil in the combustion chamber piston are out fitted with oil control rims that removes most of the oil in the cylinder walls this valves is valve stem seals and prevent  excess oil from  entering through valve stem seals various gasgets  oil seal between the engine stationary moving parts heating preventing oil from exceeding the engine (rear covers and rear crank shaft oil seals)
finally keep in mind oil changes are crucial since oil become contaminated overtime causing it to degrade so change your oil regularly from long dues of dirt oil result in severe engine vared.