MOSIL Lubricants

The Difference Between Synthetic Oil and Mineral Oil

August 11, 2025

Let us find an answer with better understanding of technical concepts for selection of synthetic oil and mineral oil

The industries are evolving in this era as well as the equipment’s are also evolving with changes and requirement of better and more optimum lubricant. The lubricant industry is also evolving and new developments are seen in lubricants one of them is oils.

A big debate is going in the industry on changing preference between mineral oil and synthetic oil. It has two sides of the coin as mineral and synthetic have their pros and cons. For understanding better we must first understand the difference between synthetic oils and mineral oils

What is Mineral Oil?

Crude oil, popularly known as petroleum oil, is pumped from the earth, refined and sold as a lubricant. Despite the refining process, which is imperfect, contaminants that are not beneficial for the machine will be introduced using petroleum oil. Petroleum oils contain a different-sized molecular structure that contains properties both beneficial and non-beneficial.

What is Synthetic Oil?

Synthetic oil is manufactured in a laboratory, i.e man-made with organic and inorganic base oils and tailored that contains a uniform-sized molecular structure and is pure from any of the non-beneficial properties found in conventional petroleum oils. Before being introduced to automobiles and industries, synthetic oils were first used in fighter jets.

To understand better we will see the molecular structure of both the oils

Now the question lies on which are the basic and important parameters to be observed while a selection of oil and their significance w.r.t each other

Base oil viscosity
Viscosity index
Temperature of application
Flashpoint
Pour point
Start-up protection
Foaming of lubricating oil·
Oxidation stability

What is Viscosity?

Viscosity is the resistance to flow offered by one layer to another layer of fluid.

What is Base Oil Viscosity?

Base oil viscosity is resistant to flow offered by lubricating oil. We have high base oil viscosity and low viscosity depending upon application we can choose the viscosity of oil to be used.

Eg: High speed and low load application – low viscosity
Slow speed and high load application – high viscosity

What is The Viscosity Index?

Viscosity index (VI) is a change in viscosity with respect to temperature. Lower the VI, more viscosity changes with temperature. Higher the VI, less viscosity change with temperature

The Viscosity index of Synthetic oil is better than Mineral oil. Mineral oil’s VI is nearly 94 – 97 while Synthetic oils VI are above 110.

By the graph of temperature Vs Viscosity, we can observe that the change in viscosity of Mineral oil is higher as cored to synthetic oil.

Conclusion: Synthetic oil will perform better during extremes of temperature and viscosity will change less within the temperature

What is The Temperature Of Application?

The temperature of application is the actual temperature that the lubricating oil has to continuously sustain throughout the working process of equipment. As the temperature influences the relubrication interval of lubricating oil and base oil viscosity as well

lubrication interval of equipment. Unlike mineral oil, which must be changed every

500 to 8,000 working hrs? Based on application, synthetic oil can go 6,000 to 70,000 working hrs. between oil changes. Longer oil change intervals mean fewer oil changes which lead to a reduced waste-disposal problem that comes with changing your oil.

What is Flashpoint?

Flashpoint of oil is the temperature at which the vapour of lubricating oil can spark. It influences the maximum operating temperature of the lubricating of oil and volatility as well.

What is Pour Point?

Pour point is the minimum temperature of lubricant when it ceases to flow and becomes highly viscous to flow. It influences the lowest minimum temperature of application of the lubricant

Fire resistance is a major requirement from industries. Here we have to use synthetic oils. The property which propagates fire resistivity is a flashpoint. Synthetics generally have a higher flash points than mineral oil since they are refined for decreasing the undesirable properties that are usually observed in mineral oil.

Synthetics also show improved performance at low temperatures as compared with mineral oil i.e it has good fluidity and pumpability and does not get a freeze during low temperatures which is characterized by low pour point. It influences the start-up – torque required by machines

What is The Foaming Of Lubricating Oil?

The foaming of oil is an accumulation of air bubbles at the surface of lubrication. It is caused by excessive agitation and an inadequate level of lubricating oil. It is one of the undesirable properties of oil. Foaming is usually observed in used oils.

Foaming of oil due to agitation is less in synthetic oil as compared to mineral, as they have better anti-foaming properties.
The anti-foaming property is the one that hinders the formation of air bubbles in used lubricating oil.
As shown in the picture mineral tends to foam more as compared to synthetic oil.

What is Oxidation in Lubricants?

Oxidation is a chemical reaction of lubricating oil with oxygen. The rate of oxidation is influenced by high temperatures, acids, and water catalysts such as copper. The rate of oxidation increases with time. The service life of lubricants is also reduced with an increase in temperature. Oxidation also leads to an increase in base oil viscosity and deposits of sludge.

What is Oxidation Stability?

Oxidation Stability is when lubricants maintain their consistency and viscosity during the service life of lubricants and are not influenced by high temperature, water, and acid and presence of a catalyst.

Mineral oils are prone to vaporize, oxidize within the normal operating temperature of the machine. This is commonly referred to as breakdown. Once the oil begins to break down, it usually results in oxidation, creating hardened oil deposits more commonly known as sludge- in machine components.

Synthetic oils can withstand greater heat temperatures, resulting in greater protection against breakdown and having good oxidation stability.

There are many challenges faced in the industry we will consider one for Eg: One of the most common challenges faced by industries is oil leaks in the gearbox. Myth is all the oils are the same and the leakage will persist.

Let Us Understand the root cause behind the same

Oils tend to foam after use; Foaming is generally air bubbles being introduced on the surface of the oil. There is a generation of air pockets in oil. The same oil when comes into the contact with gears, the air pockets present in oil lead to the friction between the gears leading to heat generation.

Also Read: How To Choose A Gearbox Lubricant

Conclusion: The challenge of leakage in gear oil is due to the foaming tendency of lubricating oil.

As we understood different parameters of selection of oil and challenges faced by the industry. We can summarize synthetic oil gives better life to equipment and also increases re-lubrication interval. But the decision lies in the hands of the user which type of oil he prefers for his machines based on his requirements.