The NOACK Volatility Test is a Critical Measurement of Motor Oil Quality

AMSOIL was the first motor oil company in North America to use the NOACK volatility test to measure motor oil quality and performance. Although competing motor oil companies initially paid no attention to NOACK results, the test has since become a critical measurement tool throughout the industry.

Originally developed and used in Europe, the NOACK volatility test determines how much weight an oil loses through volatilization. The more a motor oil vaporizes, the thicker and heavier it becomes, contributing to poor circulation, reduced fuel economy and increased oil consumption, wear and emissions. During the test, the subject oil is heated to 150°C for a specified period, causing the lighter oil molecules to boil off. The results are reported in the percentage, by weight, of the oil that evaporates. The lower the number, the better the oil resists volatilization.

Because they are made from impure, irregular molecules, conventional motor oils are more susceptible to the effects of heat. The small, light molecules in conventional oil tend to evaporate (volatilize) as the oil is heated, leaving large, heavy molecules behind and leading to oil consumption and an increase in the oil’s viscosity. If those large, heavy molecules are chemically unstable, they may also break down and form deposits on component surfaces, further inhibiting the release of heat into the oil stream.

Because their formulations minimize the quantity of impure, irregular molecules, synthetic motor oils are generally more resistant to volatilization, allowing them to perform better than conventional oils in the NOACK volatility test. However, due to varying qualities of base stocks and additives, not all synthetic motor oils perform the same in the NOACK test.

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