This "chemical soup" found in standard petroleum mineral oils contributes to many of their shortcomings when compared with synthetic oils. Because these molecules prevent uniformity, the oil has a tendency to deteriorate more rapidly. If lighter fractions are present in the oil, they can boil off (or volatize) which leads to oil consumption, oil thickening and a loss of performance.

For example, if an automobile needs five quarts of mineral oil sold at $2 a quart to operate during a 3,000- mile drain interval, and the mineral oil used in the vehicle volatizes and is replaced at a rate of one quart every 1,000 miles, the automobile actually goes through 7 quarts of mineral oil during the drain interval and the motorist spends an extra $4 per oil change interval on "topping off" the levels. Considering that the average vehicle puts on 15,000 miles a year, $20 in extra oil is used to keep the oil levels sufficient.

But extra oil is not the only expense motorists face when dealing with volatization. As motor oil goes through the process of volatizing, the chemically lighter (or more volatile) portions are always the first to "boil off" in the oil. This leaves the heavier, less pumpable portions behind. This heavier oil cannot be relied upon to flow easily and quickly to all of the engine components. The end result is decreased fuel efficiency, premature component wear and deposit formation within the engine. The expense to the motorist can be quite substantial.

The Synthetic Solution
Synthetic motor oils have a natural advantage over petroleum-based oils when it comes to volatility. This is because synthetic oils are designed to have uniform chemical structures. This eliminates the extra chemicals and hydrocarbon structures (or "chemical soup") found in oils based only in mineral stock. Because they contain less lighter chemical portions to boil off, synthetic products lose less of their lubricating abilities to volatization.

AMSOIL Synthetic Motor Oils maintain their viscosity and provide ongoing cold start protection, fuel efficiency and reduced oil consumption.

The test has different passing requirements depending on the weight of the oil being tested. For example, 10W-30 oil in the United States may lose up to 22 percent, by weight, and still be "passable." However, with 20 percent gone, the oil suffers significant performance deficits in characteristics such as pumpability and lubricity.

Effective July 1, 2001, a new specification, known as GF-3, allows a maximum of 15 percent loss. European standards, which have been stricter for years, already limit high quality oils to a maximum of 13 percent loss. AMSOIL 10W-30 loses only 6.76 percent to volatility.