All of us have seen countless ads telling us to change our engine oil every 3000 miles. Some of us have watched the infomercials showing cars driving on the racetrack with allegedly no oil or engines running on a stand while the host pours sand and gravel over an exposed valve train. Virtually all of the lube shops have some kind of magic additive that they will say you need. What are we to believe? Or more relevant, what is right for you? In becoming an Amsoil Synthetic Lubricants dealer in 1998 I have done a great deal of research on all kinds of lubricants and additives and in this article I will share the facts about synthetic oils, petroleum based oils, and additives so that you can make an informed decision about what is right for your cars.
There are two systems for oil classification. The SAE (Society of Automotive Engineers) viscosity grade and the API (American Petroleum Institute) classification that designates the type of engines for which the oil was designed. The SAE viscosity grade is known as the “W” or “winter” number when classifying oils. Most oils on the shelf today are multi-viscosity such as 10W30 or 20W50. In general, the lower the first number, the better the oil will perform in extremely cold conditions. Conversely, the higher the second number the better the oil will protect at higher temperatures. If you were driving to Minnesota in the winter you would want the lowest number you could find like a 0W30. In our Florida climate however, a 10W40 or a 20W50 would be a better choice. The API designation is typically an “S” (spark fired) designation for gasoline engines and a “C” (combustion fired) designation for diesel engines. Most of today’s oils carry an SH,CF or SJ,CF designation signifying that they are suitable for use in all gasoline or diesel automotive applications. Those of you with diesel trucks or motor homes should look for an API CG-4 rated oil. Which brand you buy is largely a matter of preference. Consumer Reports (6/97) found very few differences between major brands of petroleum based oil and all with the above SAE and API designations performed fine in normal applications.
Synthetic oils were originally developed more than 50 years ago and became widely used in jet engines. Less than -120°F ambient temperatures, 60000 shaft rpm, and 500°+F exhaust temperatures proved too much for conventional oils. Synthetics were created specifically to withstand these harsh conditions and to date every jet engine in the world uses synthetic lubricants. Amsoil introduced the first synthetic oil for automotive use in 1972 and have continued to be at the leading edge of development ever since. Mobil-1, undoubtedly the most recognized name in synthetics, was introduced in 1976. Many companies have jumped on the bandwagon and have since released synthetic lubricants for automotive use and all are becoming increasingly popular for their superior lubricating properties, superior ability to flow at cold temperatures, and their ability to withstand high temperatures for extended periods of time. Several new cars including the Porsche 996 and the Chevrolet Corvette LT-1 are delivered with synthetic oil in the crankcase and require synthetic oil use throughout the life of the car.