Hot Temperatures

SIGNIFICANT CHALLENGE FACED by today's motor oils is maintaining an adequate level of protection during high-temperature conditions. Without a quality motor oil protecting it, an engine can be damaged through motor oil breakdown, viscosity increase, and deposits - all caused by excessive heat.

All motor oils are subject to vaporization when exposed to high heat. How much an oil vaporizes is measured by the NOACK Volatility Test (ASTM D5800). Conventional motor oils tend to vaporize the most, the lightest fractions evaporating first and leaving behind a thicker, harder-to-pump motor oil. The uniformly sized molecules of synthetic motor oils are much more resistant to vaporization. Less oil evaporates and viscosity remains consistent.

The flash point of a motor oil is the lowest temperature at which application of a flame will cause lubricant vapors to ignite. Higher quality base stocks exhibit higher flash points, and the higher a motor oil's flash point, the better the protection.

AMSOIL motor oils are formulated with high flash points, keeping volatization to an absolute minimum and maintaining their superior protective and performance qualities in extreme heat conditions. In fact, a look at the chart shows AMSOIL 10W-30 Synthetic Motor Oil loses significantly less of its original weight during high-temperature service when compared to competing motor oils.

As motor oils operate in high heat, especially over extended periods, they tend to thin out and lose their ability to provide adequate wear protection. Viscosity Index (VI) indicates the degree of an oil's viscosity change over a given temperature range (between 40°C and 100°C). The higher a motor oil's VI number, the better it is able to maintain its viscosity over a broad temperature range, translating into better wear protection in both hot and cold temperatures. Motor oils with a low VI do a poor jog of maintaining viscosity in extreme temperatures, while they are very thin at high temperatures.

Motor oils formulated with synthetic base stocks usually have naturally high VI numbers, giving them the ability to resist viscosity change in high-temperature operation. Conventional motor oils, on the other hand, require high amounts of VI improvers that increase the relative viscosity of motor oils during high-temperature operation. Viscosity improvers can be thought of as springs, coiling at cold temperatures and uncoiling in high temperatures. Uncoiling makes the molecules larger, increasing internal resistance within the thinning oil and reducing the overall viscosity loss of the fluid.

AMSOIL Synthetic Motor Oils have "ultra high" viscosity indices, allowing them to stay in grade and provide superior wear protection throughout extended drain intervals. In fact, AMSOIL 10W-30 Motor Oil was recently subjected to a triple length Sequence IIIF test. Even after being subjected to the test three times longer than the standard length, AMSOIL 10W-30 performed three times better than the standard limits. The competitor's motor oil showed dramatic viscosity increase in less than half the time.

Oil heated in the presence of air oxidizes, forming damaging acids and deposits. The higher the temperature, the higher the rate of oxidation. Oxidation inhibitors are added to motor oils to minimize the high-temperature deterioration process, while detergents and dispersants minimize the formation of sludge and deposits, neutralize acids and hold solid contaminants in suspension.

AMSOIL Synthetic Motor Oils are formulated with the highest quality additive packages, resisting the damaging effects of heat and oxidation much longer than conventional motor oils, and keeping engines running clean and deposit-free.

Part 2 - Cold Temperatures