Petroil Lubrication System | Petroil Lubrication System Diagram.

Petroil lubrication system is the oldest and the simplest lubricating system. It was basically used in motorbikes. In this article, I will discuss the petroil lubrication system.

Petroil Lubrication System

Petroil Lubrication System

This system of lubrication is generally adopted in two-stroke petrol engines, like scooters and motorcycles. It is the simplest form of the lubrication system. It does not consist of any separate part, like an oil pump, for the purpose of lubrication.
But the lubricating oil is mixed in the petrol itself while filling in the petrol tank of the vehicle, in a specific ratio. When the fuel goes into the crank chamber during the engine operation, the oil particles go deep into the bearing surfaces and lubricate them. The piston rings, cylinder walls, piston pins, etc. are lubricated in the same way.
If the engine remains unused for a considerable time, the lubricating oil separates off from petrol and less clogging of passages in the carburetor, resulting in engine trouble. This is the main disadvantage of this system. 

Petroil Lubrication System Diagram

Petroil Lubrication System Diagram


How Petroil Lubrication System Works?

Petroil lubrication system works on the dual-layer lubrication system. In this method, the two particles mix with each other but work for different purposes. 
This lubrication system basically works on the two-stroke engine. In this engine, the crankshaft and the whole part move in a single cylinder. When the petrol was filled to the engine the engine oil also filled with the fuel.
The fuel and oil mixture then goes into the engine port and the oil drains down to the crankcase. The density and the viscosity of the oil are much higher than the petrol. So that the oil drained into the last part of the engine. 
When the engine rotates it lubs its parts during the operation. But some of the parts do not get the proper lubrication and some of the oil also burns with the fuel. This system does not require any oil pump or any other mechanical or electrical equipment. 

Advantages of Petroil Lubrication System

By combining the benefits of synthetic and petroleum-based lubricants, the Petroil system maximizes machinery performance, leading to enhanced productivity and efficiency. The advantages are- 
  1. This type of lubrication is very simple.
  2. The maintenance cost is minimum.
  3. The Petroil Lubrication System’s design incorporates the use of synthetic lubricants, which are more environmentally friendly compared to conventional petroleum-only solutions.
  4. There is no need for any other material for lubrication so the cost cutting of the bike is very common. 
  5. The lubricant is also available at petrol stations. 


Disadvantages of Petroil Lubrication System

If there are some advantages then are certain disadvantages also. The disadvantages are- 
  1. The petroil lubrication system does not provide the proper air-fuel mixture. 
  2. The engine oil mixes with the fuel all the time causing engine damage. 
  3. The effectiveness of the petroil system heavily relies on the quality of the oil used and the accuracy of the oil-to-fuel mixture.
  4. In this type of lubrication system, the engine deposits the carbon into the combustion chamber.
  5. The addition of oil to the fuel mixture reduces the overall energy content of the fuel, resulting in slightly reduced fuel efficiency compared to a separate lubrication system where oil is not mixed with the fuel.


The petroil lubrication system was the simplest lubrication system in automotive history. But the tendency to the emission makes this lubrication system discontinued. 
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