Does the color of the lubricant have a significant impact on its properties?

Colors accompany people throughout their lives, already in childhood we learn certain behaviors based on them, e.g. green means we can cross the street, and red means we have to stop. We often associate color with quality - we subconsciously choose a product with a color that we believe indicates, for example, better taste, although the actual situation may differ from our expectations.

Similar sentiments arise in the context of the lubricants industry. When asked to specify the requirements for the grease or oil he needs, the customer sometimes mentions its color even before the specifications it has to meet. We can therefore conclude that color has a significant impact on our choices, even in the lubricants industry.

In fact, for some products it matters. A specific color is used to make certain products easy to distinguish from others, which, if mistaken, could cause a serious failure of a given system. A good example is oils for automatic car transmissions. They are usually colored red to make them easier for the user to identify. Color is also important in the case of two-stroke engine oils. In this case, its saturation is more important than the color itself - it is intended to help users determine whether the appropriate amount of lubricant has been added to the fuel and whether the resulting mixture is homogeneous. Typically, these oils are red or green in color with appropriate saturation.

In the context of lubricants, the color of the oil is also associated with its viscosity; darker oil is often perceived as more viscous. This is due to the colors of group I base oils, which range from light yellow (usually lower viscosity oils) to dark brown (usually higher viscosity oils). Currently, however, the lubricants industry is moving away from the use of group I oils, their market share is decreasing in favor of oils of groups II and III, and also, although to a lesser extent, in favor of synthetic bases of groups IV and V. In the case of the latter, there is no longer any dependency between viscosity and color, hence color, which was once related to viscosity to some extent and could be an approximate reference point for the approximate determination of viscosity - currently cannot be taken into account as a parameter indicating the viscosity of products. Additionally, the color of the final lubricant products is also influenced by the additives used, including: detergents containing calcium sulfonate and additives containing magnesium or molybdenum.

To sum up, it should be stated that only the standards and specifications indicated by the manufacturer should be used to assess the quality and suitability of a lubricant for a specific application, and the color of the product can only be taken into account in a few cases of products with specific applications, when its shade or intensity is determined by the specifications. In the case of other products, it does not provide information that is important to the user.

Michał Świątek

[1] D. Saraiva, The Importance of Colour in the Lubricants Industry, “Lube Magazine” 2018 (August), No. 146, p. 14-15.
[2] K. Bannister, The Color of Lubrication, “Efficient Plant Magazine” 2016 (June).

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