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Mineral oils are derived from the refining of crude petroleum. During the process, natural contaminants and unwanted hydrocarbons are removed.

Mineral oils are ideal for older vehicle models. They offer the advantage of low cost.

However, mineral oils flow through the engine circuit more slowly. This results in increased fuel consumption and impacted vehicle performance. Mineral oils also need to be changed more frequently than synthetic oils. However, mineral oils are quality oils that are largely sufficient if recommended by your automotive manufacturer.


Synthetic engine oils are a product of complex chemical transformations that are performed either directly on crude petroleum extracted by drilling, or using preselected molecules. The difference with mineral oils resides in the transformation process: synthetic oil undergoes more sophisticated modifications.

Composition of synthetic engine oils

Key points on synthetic oils:

  • They contain fewer impurities than mineral oils;
  • They are chemically modified.

For both types of oil, additives are added to significantly improve the oil’s performance. The additives can protect against wear, oxidation, corrosion, or foam, or provide detergents or dispersants.

Synthetic oils are mainly designed for high-performance engines.

What are the advantages of synthetic oils?

Synthetic oils offer many advantages:

  • Excellent flow at low temperatures;
  • Stable viscosity, even at high temperatures (synthetic oils do not fluidify easily);
  • Less frequent oil changes;
  • Less formation of deposits;
  • Less wear on parts;
  • Optimized fuel consumption;
  • Protection of engine, longer lifespan.

The main disadvantage of synthetic oils is that they are slightly more expensive. All oil types are not suited to all types of engines. Before choosing between a standard mineral oil or a synthetic oil, it is important to read your automotive manufacturer’s recommendations.


Engine oil viscosity

Engine oil viscosity refers to how easily oil pours at a specified temperature. Thin oils have lower viscosity and pour more easily at low temperatures than thicker oils that have a higher viscosity. Thin oils reduce friction in engines and help engines start quickly during cold weather. Thick oils are better at maintaining film strength and oil pressure at high temperatures and loads.

Measuring engine oil viscosity

The Society of Automotive Engineers developed a scale for both engine (motor oil grades) and transmission oils.

Viscosity is notated using the common classification “XW-XX”. The number preceding the “W” (winter) rates the oil’s flow (viscosity) at zero degrees Fahrenheit (-17.8 degrees Celsius). The lower the number, the less the oil thickens in cold weather.

The numbers after the “XW” indicate viscosity at 100 degrees Celsius and represent the oil’s resistance to thinning at high temperatures.

For instance, oil with a 5W-30 grade thickens less than oil with a 10W-30 grade in cold weather. Oil with a 5W-30 grade thins out more quickly at high temperatures as compared to oils with a 5W-40 grade.

During winter and for cars used in cooler regions, your engine will benefit from using oil with low winter viscosity. During summer and in hotter regions, your engine will benefit more from oil with higher viscosity at 100 degrees Celsius.

When comparing oils, it is important to take into account the location in which the car will be used. Thin oils that are less prone to thickening in low temperatures will help you start your engine more quickly in winter while thick oils that are less prone to thinning in hot temperatures will help your engine perform better  in summer.  As a result, 0W-20 and 5W-30 oils have been developed for colder climates while 15W-40 and 20W-50 oils have been developed with hotter climates in mind.