What is Engine Lubrication System?- Types & Uses

The engine lubrication system is to distribute oil to the moving parts to reduce friction between surfaces. Lubrication plays a key role in the life expectancy of an automotive engine.

What it does is – reduce friction between the two surfaces. Lubrication further plays a significant role in the life expectancy of the automotive engine. Now, it is extremely important that the lubrication system is effective and functioning all the time because if the lubricating system fails, an engine would fail to perform to its optimal level due to overheating and thus it would seize very quickly.

Let us understand more about the process and components in detail which is not easily available and thus not everyone knows or understand the functioning for an engine lubrication system, our purpose through this article is to educate everyone who is looking for detailed information on the engine lubricating system.

How an Engine Lubrication System Works?

The process of lubrication in an internal combustion engine begins in the sump, commonly referred to as the oil pan. From here, the oil is pulled through a strainer, by the oil pump, removing larger contaminants from the mass of the fluid. The oil then goes through the oil filter. It is important to note that not all filters perform the same.

A filter’s ability to remove particles is dependent upon many factors, including the media material (pore size, surface area and depth of filter), the differential pressure across the media, and the flow rate across the media.

Oil is pumped through passageways to the various components of the engine such as the cam, main bearings, rod, pistons, etc. Gravity then pulls the oil back down to the bottom of the motor to drain back into the sump, and the cycle repeats.

Why is it important to lubricate an engine?

The three major functions that lubricants perform are:

Reducing friction is what most people would think of when asked what a lubricant does. With all its parts that move quickly and very close to each other, an engine would not survive for long without a lubricant to ‘smoothen things up’.

Cooling is necessary because a working engine heats up to high temperatures. Without a lubricant, it would break down from the heat it produces itself!

Cleaning concerns the impurities that exist in an engine. Combustion, the process that takes place inside an engine, produces soot and contaminants. Without lubricants these would form large deposits in the oil block passage, hindering the engine’s performance as a result.

Engine Lubrication System Components

Let’s follow Oliver the Oil Molecule on his journey around the engine!

How an Engine Lubrication System Works
  • Oil pan: This is where Oliver hangs out when the engine isn’t doing anything; the oil lounge, if you will. In most cars, this pan holds about 4 to 6 quarts of oil.
  • Pickup tube: When the engine is switched on, it needs oil immediately. Oliver and his oil buddies get sucked up by the pickup tube and lined up for action.
  • Oil pump: The pump does the sucking so that Oliver can slide up that tube against gravity and then pressurizes the oil. Oliver and his little oil friends get jammed in together even closer. Let’s hope Oliver remembered to put on deodorant today.
  • Pressure relief valve: If Oliver and his friends get too close they start to plan a riot, this relief valve gives them a bit of much-needed breathing space. It’s the lubrication system’s way of saying, “Settle down, kids.”
  • Oil filter: While Oliver and his friends are allowed to pass into the engine, the filter stops any dirt and debris the oil may have picked up on its last pass through the system.
  • Spurt holes and galleries: Oliver giggles every time he says “spurt holes.” He’s really immature. These are the little holes drilled in the crankshaft or other parts of the system that allow the oil to coat the bearings and cylinders that need to stay lubricated.
  • Sump: After doing his job to keep the moving parts of the engine moving, an exhausted Oliver slides all the way down into the oil pan again, also known as the sump, to hang out until he’s sucked back up the pickup tube — and he’s back on the job.

Types of Lubrication Systems:

The lubrication system can be classified into the following ways:

  1. Petroil system
  2. Splash system
  3. Pressure system
  4. Semi-pressure system
  5. Dry sump system and
  6. Wet sump lubrication system

1. Petroil Lubrication System:

  • This system is generally used in the two-stroke petrol engines like scooters, motorcycles.
  • In this type of system, a certain amount of oil is mixed with petrol itself. therefore 3 to 6% of oil mixed with fuel.
  • This proportion should be proper. If this proportion is less, the danger of oil starvation causes damage to the engine.
  • If this proportion is more, the engine gives dark smoke and excessive carbon deposits on the cylinder head.

2. Splash Lubrication System:

  • This is the most popular type of lubrication system duly used in cars extra.
  • This is one of the cheapest methods of the lubrication system.
  • It consists of a scoop, which is fitted at the lower end of the connecting rod as shown in the diagram.
  • As when the engine runs scoop splashes, the oil from oil through by centrifugal force to all engine parts.

How Does Splash Lubrication System Work?

Splash lubrication system is used on small, stationary four-stroke engines.

In this system, the cap of the big end bearing on the connecting rod is provided with a scoop that strikes and dips into the oil-filled through at every revolution of the crankshaft, and oil is splashed all over the interior of the crankcase into the piston and cover the exposed portion of the cylinder is shown in the figure below.

A hole is drilled through the connecting rod cap through which the oil passes through the bearing surface.

Oil pockets are provided to catch the splashed oil over all the main bearings and also the camshaft bearings.

From these pockets, oil passes to the bearings through a drilled hole.

The surplus oil dripping from the cylinder flows back to the oil sump in the crankcase.

3. Pressure Lubrication System:

  • This system is used, because the splash system is not sufficient for larger engines like Ambassador, Jeep, Ashok Leyland, and others.
  • Oil from the sump will be supplied to the engine parts through main galleries, via strainer and filter.
  • The pressure of oil is about 2 to 4kg/cm2.
  • For camshaft and timing gears, oil is supplied by a separate line through the pressure-reducing valves.
  • In this type of system, oil is pressurized by using a gear pump

4. Semi-Pressure Lubrication System:

  • In this type of system, the oil pressure is between 0.4 to 1 kg/cm2.
  • In this system, some parts are lubricated by the splash system and some parts are by a pressure system.
  • The parts such as cylinder wall, piston, piston pin, connecting rod extra are lubricated by a splash system and remaining parts are by a pressure system.

5. Dry Sump Lubrication System:

This system consists of two pumps.

  • One scavenging pump placed below the sump, other pressure pump placed at the tank.
  • Scavenging pumps supply lubricating oil to the main tank through the filter and, a pressure pump supplies oil to the different parts of an engine through the oil cooler.
  • A dry-sump system gets you a couple of bonuses: First, it means the engine can sit a little lower, which gives the car a lower center of gravity and improves stability at speed.
  • Second, it keeps extra oil from soaking the crankshaft, which can lower horsepower.
  • And, since the sump can be located anywhere, it can also be any size and shape.
  • In this system, the pressure of oil is about 4 to 5 kg/cm2.
  • Here sump is kept dry. Hence called a Dry sump lubrication system.
  • This type of system is used in the sports car, and certain military vehicles extra.
  • In brief, an engine lubrication system in which the lubricating oil is carried in an external tank and not internally in a slump.
  • The sump is kept relatively free from oil by scavenging pumps, which return the oil to the tank after cooling.
  • The opposite of a wet sump system.
  • The pumping capacity of scavenging pumps is higher than that of the engine-driven pumps supplying oil to the system.

6. Wet Sump Lubrication System:

  • In this system, the oil is delivered from the sump strainer to different engine parts.
  • In this system, the pressure of oil is about 4 to 5kg/cm2.
  • After lubrication oil is drawn back to the oil sump.
  • In this case, the oil is always present in the sump.
  • Hence called a wet sump lubrication system.
  • The advantage of a wet sump system is its simplicity. And the oil is close to where it will be used, there aren’t too many parts to engineer or repair, and it’s relatively cheap to build into a car.


What is an engine lubrication system?

The Engine lubrication system is considered to give a flow to the clean oil at the accurate temperature, with a appropriate pressure to each part of the engine.

Why does an engine need lubrication?

Engine oil must lubricate the various parts of an engine to reduce friction and minimize unnecessary loss of power. A well-lubricated engine will burn fuel more effectively and therefore perform better.

What would happen to an engine without a lubrication system?

Lubrication plays a key role in the life expectancy of an engine. Without oil, an engine would succumb to overheating and seizing very quickly. Lubricants help mitigate this problem, and if properly monitored and maintained, can extend the life of your motor.

What is the major cause of lubricating system failure?

Moisture is one of the main failures of lubricating oils because it greatly increases the oxidation rate of the lubricant. Foreign material: Foreign materials in oils such as particles very seldom affect the lubrication oils but greatly decrease the life of the equipment components.

What is the most common problem in a lubricating system?

Through visual inspections the most common cases of lubrication problems that are diagnosed are: Lubricant degradation in gearboxes. Bearings with contaminated grease or over-greased. Contamination of lubricant with metallic particles in gearboxes or bearings.