Modern engines, particularly those equipped with performance-enhancing technologies like direct fuel injection and turbochargers, generate increased heat compared to their predecessors. At elevated temperatures, such as during severe service or when driving in hot summer weather, the oil’s lighter-weight molecules can volatilize, or “boil off.” The more volatile a lubricant, the lower the temperature at which it will begin to evaporate. The more it evaporates, the less oil is left to protect equipment and the faster a user must replace the lost oil. You may have experienced this phenomenon if you’ve owned an automobile that “uses” motor oil in irregular intervals.
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.
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