How does Temperature Affect Viscosity in Motor Oil?

Temperature impacts the viscosity of many liquids but changes in salt water viscosity are quite small and are difficult to observe. Generally, as the temperature of a liquid increases, there is a decrease in viscosity and the liquid becomes more easy to pour. This is true of most liquids but how does this relationship stand with respect to the Viscosity of Motor Oil?

Viscosity of Motor Oil

Certain kinds of motor oils behave differently. Ideally, an engineer would prefer the oil viscosity to remain the same when the engine is hot as when it is cold. Motor oil includes additives developed to reduce changes in viscosity because of temperature.

Certain motor oils are designed to be thinner (less viscous) when cold and more viscous (thicker) when hot. For instance, multi-grade or multi-viscosity motor oils show a low viscosity at low temperatures and high viscosity at high temperatures.

The idea is to provide thin oil when the motor is started and to provide an oil of the right thickness at the operating temperature.

These multi-grade or multi-viscosity oils can be identified by designations such as 10-30W.

These numbers refer to specifications developed by the Society of Automotive Engineers (SAE).

The "10W" in this example corresponds to the lower oil viscosity when the engine is cold and not running. The "30" refers to the higher oil viscosity when the engine is hot and running normally.

About Fungilab

Fungilab manufactures advanced and high quality rotational viscometers. Fungilab is a strong and solid brand, recognized around the world for its best practices in products and services in the viscosity market.The values that Fungilab brand transmits to market for improving the client’s confidence are high quality equipment with an accurate, easy and evolved working system, featuring the latest advances in technology; specialized customer and technical service to differentiate fungilab from the rest of the brands in the viscosity market; pre-sales and post-sales support to end customers and dealers; and equipment repairs.


This information has been sourced, reviewed and adapted from materials provided by Fungilab.

For more information on this source, please visit Fungilab.

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