When light elements in oil evaporate from heat, the oil’s viscosity increases. This thicker oil forces the engine to work harder, resulting in several problems, including the following:
• Reduced performance
• Reduced fuel economy
• Poor cold-temperature starting
• Increased engine deposits
• Out-of-balance oil formulation, potentially leading to a higher concentration of additives than designed
The Test
In the NOACK Volatility Test (ASTM D5800), an oil sample is weighed and heated to 250°C (482°F) for one hour. Dry air is passed over the sample, carrying the oil vapors that have boiled off and depositing them in a beaker. The original sample is removed and re-weighed. Any reduction in weight is reported as a percentage lost of the original weight. A lower number indicates a better resistance to evaporation.
Keeping Volatility in Check
Signature Series has a uniform molecular structure that limits evaporation and keeps the oil where it’s needed most – protecting your engine. AMSOIL fights volatilityU 38% better than Mobil 1 and 17% better than Royal Purple, helping reduce oil consumption and keep valves clean.