What is the NOACK Volatility Test?

Volatilization is a term used to describe what happens to a fluid as it is heated to the point it begins to turn to vapor “vaporize.” Upon reaching a certain temperature, oil will begin to lose some of its lighter weight molecules as they vaporize and leave heavier weight molecules behind. Not only does this cause higher oil consumption, this process can also cause increased viscosity making the oil more difficult to circulate through the lubrication system.

The ASTM D-5800 (NOACK) is a widely accepted method of measuring volatility. Originally developed and used in Europe, the NOACK test determines how much weight loss an oil experiences through volatilization. AMSOIL INC. was the first company in the United States to use and report NOACK results in 1984. Today, the NOACK test is a requirement for API SM and ILSAC GF-4.

In the NOACK test the oil is heated to 150° C (302° F) for one hour. The lighter oil fractions will vaporize leading eventually to oil consumption, oil thickening and a loss of performance. The test reports results in the percentage, by weight, lost due to "volatilization."

For example, before July 1, 2001, 5W-30 motor oil in the United States could lose up to 22 percent of its weight and still be regarded as "passable." Now, with GF-4, the maximum NOACK volatility for API licensing is 15 percent. European standards limit high quality oils to a maximum of 13 percent loss. AMSOIL 10W-30 loses only 5.44% percent of its weight, reducing oil consumption, oil thickening and retaining performance.

Sample NOACK Testing Graph