by Curt Scott,
an article from: "The Complete Guide To Specialty Cars".

"Those naysayers who only a decade or so ago prematurely dismissed synthetics as, "snake oil", are now among the staunchest devotees of laboratory-manufactured lubricants. Among these believers are top lubrication engineers, race car drivers, vehicle fleet operators, and millions of private motorists around the world. What factors have contributed to the growing enthusiasm for synthetic lubricants? Simply put, synthetically-produced lubricants have demonstrated beyond doubt that they are far superior to their conventional petroleum counterparts in fulfilling the many and varied tasks demanded of oil by today's modern engines and powertrains. Indeed, synthetic lubricant technology is swiftly progressing to a point where it is possible that engine wear may no longer continue to be the major limiting factor in the expected life span of motor vehicles."

"The first question demanding an answer is: Just what is synthetic oil? Technically speaking, synthetic lubricants are made by chemically combining, in a laboratory, lower-molecular-weight materials to produce a finished product with planned and predictable properties. Don't be confused by this technical double-talk. What this means is that synthetics are custom-designed products in which each phase of their molecular construction is programmed to produce what may be called "the ideal lubricant." This process departs significantly from that of petroleum lubricants, whose physical components, both desirable and undesirable, are inherited from the crude oil from which they are refined.

Crude oil possesses thousands of varieties of contaminants, depending upon the oil's geographical and geological origins, which no amount of refining can entirely remove. Corrosive acids, paraffins and other waxes, heavy metals, asphalt, napthenes and benzenes, as well as countless compounds of sulfur, chlorine, and nitrogen, remain in the finished product.

Equally as important, petroleum oil molecules, as contrasted to uniform-sized synthetic oil molecules, vary significantly in size, shape and length. When your engine heats up, the smaller molecules evaporate, while the larger ones tend to oxidize and become engine deposits. As a result, refined petroleum lubricating products differ widely in their overall quality and performance. The presence of and the resulting drawbacks of these undesirable constituent elements lie at the very root of the considerable performance differences between synthetic and petroleum based motor oils."

"Chief among the areas in which the pre-planned and predictable properties inherent in premium synthetic lubricants significantly surpass those of premium petroleum oils are: low-temperature fluidity...and thus improved ambient startup protection; low volatility, (higher boiling point...greater resistance to evaporation); high-temperature thermal stability; oxidation resistance; lubricity; fuel economy; film strength and wear protection; extended drain capabilities; water stability; and high natural detergent characteristics, (resulting in a cleaner engine with less additive content)."

"For the purposes of comparison, we have taken a well-known synthetic engine oil, Amsoil 10W-40 synthetic oil, and contrasted its characteristics with those of several prominent 10W-40 conventional motor oils. Below is a condensed summary of the results of several closely-monitored field and laboratory tests:

Amsoil 10W-40
100% synthetic


Effective lubrication range
-60 F to +400 F
0 F to 300 F
Viscosity increase after single sequence, (64hour), Olds III-D Test
102 to 400%
Wear, (mg. weight loss Falex test)
1.1 mg.
3 to 6mg.
Fluidity @ - 40 F
Flows freely
Volatility, (evaporation @ 300 F for 22 hours)
Crankcase Temperature (Track test)
240 F
290 F
Flash Point (D92 Test)
470 F
400 F<
Oil consumption, (50,000 mile test)
42% less than
Intake valve deposits, grams measured at 50,000 miles.

"From this data it is readily apparent that synthetic lubricants have substantially broadened the horizons of engine lubricant protection. Simply by comparing the lubrication-temperature range comparison, the limits of petroleum lubricants become evident. On both ends of the relavent temperature spectrum, synthetics demonstrate conclusively the ability to significantly extend the thermal regions in which the engine is protected. This has a special significance for those automotive power-plants which normally work harder and produce higher internal and lubricant temperatures...that is to say: high-performance engines, smaller high-RPM engines, air cooled engines, diesels and rotaries. Furthermore, climactic conditions in which synthetics allow operation with full engine protection are for all practical purposes boundless, whereas with a petroleum oil the protective capacity significantly diminishes with temperature extremes. Note particularly the comparative viscosity, (oil thickening), increases after the 64-hour Olds III-D test, (Item 2)... 9% for the Amsoil synthetic VS 102-400% for the multigrade petroleum oils; the reduced wear, (Item 3), and the reduction in crankcase temperatures, (Item 6). These favorable results are quite typical of virtually all similar test comparisons between petroleum - and synthetic-based motor oils."

"Underhood temperatures also take a quantum leap with the use of power options, especially air conditioning, and because of emissions devices and emissions-related design. It is important to note that, even though the dash gauge may register only a 200 deg. F or so water/coolant temperature, the temperature of the sump and of all the assorted bearing surfaces significantly exceed the water temperature, and often surpass 500 deg. F on the piston ring and cylinder wall areas. These high-temperature surfaces serve to rapidly decompose petroleum oil and additives, as well as contribute to their shorter service life, while the synthetic is largely unaffected. Beyond the protection afforded an engine during these particular instances of high-operating temperatures, high-temp thermal stability moreover permits an engine oil to deliver overall extended service life, (significantly longer drain intervals), in all driving conditions, because it prevents the phenomenon of sludge and carbon formations on critical engine parts, (valves, valve guides, oil channels, lifter assemblies, piston rings, etc.), due to oil thickening, a problem commonly attributable to petroleum oil breakdown at high temperatures. As these deposits accumulate in the oil circulatory system, oil flow drops, thus accelerating engine wear. To the user of synthetics, the benefits are, (1) reduced wear of critical engine components; (2) significantly reduced sludge and varnish...a cleaner engine; (3) reduced engine drag due to uniform viscosity; and, (4) increased fuel economy due to reduced component wear."

"Film strength", refers to the amount of pressure required to force out a film of oil from between two pieces of flat metal. The higher the film strength, the more protection is provided to such parts as piston rings, timing chain, cams, lifters, and rocker arms...wherever the lubricant is not under oil system pressure. Synthetics routinely exhibit a nominal film strength of well over 3,000 psi, while petroleum oils average somewhat less than 500 psi. The result is more lubricant protection between moving parts with synthetics."

"Viscosity is a crucial consideration when improvements in fuel economy are desired. It stands to reason that the freer an engine turns, the less fuel it will require to accomplish a given amount of work. Studies have demonstrated conclusively that engine drag is directly related to the viscosity of the motor oil. Generally speaking, the lower the viscosity, the better the fuel economy of the engine. In formulating lower viscosity oils, it has become clear that the synthetics are the base stock of choice. This is because it is possible to produce a synthetic oil of a given low viscosity without incurring the excessive oil consumption, (due to evaporation), and resultant thickening of the same low-viscosity petroleum oil. Indeed, the U.S. Department of Energy in its pamphlet entitled, "An Assessment Of The Effects Of Engine Lube Oils On Fuel Economy", states: "It is evident that low-viscosity oils will help minimize engine friction losses in the prevalent hydrodynamic region and thereby achieve better fuel economy. In addition, such oils help to reduce friction during ambient, (cold), start by increasing the oil flow rate to critical engine parts. However, low-viscosity engine oils, blended from conventional petroleum base stocks, may have problems with high oil consumption and engine wear. There is also the possibility of decreased catalytic-converter life and efficiency due to the increased levels of phosphorus in the exhaust gas from the oil additives. One solution is to mix some synthetic with the mineral, (petroleum), oil, or use a synthetic base stock entirely...(end of quote). This low-viscosity, low volatility character of synthetics has become increasingly important because many automobile manufacturers are now recommending lighter-weight, (chiefly 5W-30), oils for use in their products, and because the trend toward smaller engines creates substantially more heat and stress on the oil used. In these smaller, high-output powerplants, enough heat is generated to cause a lighter petroleum lubricant to evaporate and significantly increase viscosity within weeks of its introduction into the crankcase. High-temperature stability, as well as oxidation-resistance, is of absolutely paramount importance when it comes to turbocharged engines. Because it must both lubricate and cool the turbo unit, the oil MUST be specifically formulated to withstand the turbo's extremely high operating temperatures. Oil film temperatures often exceed 450 deg. F in the turbo unit during operation, and can surpass 650 deg. F, (!!!), during a short period immediately following engine shutdown...both figures far exceeding the thermal limits of petroleum oil. Synthetics, with their capacity to maintain proper, (low), viscosity and lubricity under these high heat and stress conditions, and with their natural resistance to oxidation, have risen to the fore. It is also important to note that the high-temperature-stability properties of synthetics are designed primarily into the base-stock oil itself, rather than being achieved primarily with additives. The advantage of this approach is twofold:, (1) Additives, which may account for as much as 24% of the volume of a can of petroleum oil, by themselves have little or no lubricating properties per se. Thus the more the additive content in an oil, the less lubrication is available to the engine; and, (2) Most additives tend to volatize, (evaporate), and deteriorate with heat, age and use, so that the overall effectiveness of the lubricant itslef is significanlty diminshed within only a few thousand miles of driving.

It is also important to note that, contrary to what many take for granted, higher viscosity in and of itself does not translate into better engine protection. Extensive testing has shown the opposite to be in fact true. As long as a lower-viscosity oil is formulated to resist evaporation and provide high film strength, this lighter oil will actually deliver more complete protection to the engine parts, since its more rapid circulation delivers both better lubrication per se, and far better cooling characteristics...a critical advantage, given that oil flow furnishes up to 30% of an engines cooling requirements. Prior to the introduction of synthetics, however, the problem of evaporation, (and the resultant thickening of the remaining oil), was addressed primarily by increasing viscosity. In short, don't be concerned with the relatively lower viscosity ratings of some synthetics. Syn lubes are a whole new ball game.

The remarkable ability of synthetic oils to reduce internal operating temperatures is far too important to ignore, since high operating temperatures contribute directly to premature failure of mechanical components and gaskets and seals. Coolant, (i.e. water/antifreeze), cools only the upper regions of an engine. The task of cooling the crankshaft, main and connecting rod bearings, the timing gear and chain, the camshaft and its bearings must be borne entirely by the oil. There are three identifiable reasons why synthetics do a better job of cooling an engine: (1) Because of both the oil's lubricity, (slipperiness), and its stable viscosity, less friction - and thus less heat - is generated in the first place; (2) The molecular structure of the oil itself is designed to more efficiently transfer heat, even compared against the thermal conductivity properties, (ability to absorb and dissipate heat), of an identical viscosity petroleum oil; and, (3) As mentioned in the preceeding paragraph, the more rapid oil flow of these lower-viscosity synthetics contributes significantly to the efficient transfer and dissipation of heat. Because of all these factors, oil temperature decreases of from 20 deg. F to 50 deg. F are quite common with the use of synthetic oil. One might even say that the heat-reduction properties of synthetics are synergistic...by helping to reduce its own temperature, the synthetic oil is simultaneously enhancing the lubricant's overall performance characteristics."

"In the same Popular Science article on synthetic oils, veteran race car driver Smokey Yunick was quoted: "When you disassemble an engine that's been run on petroleum oil, if you examine the rings and cylinder bores with a glass you'll see ridges and scratches - that's the wear going on. With a polyol, (a variety of synthetic), when you take the engine apart everything has the appearance of being crome-plated. In the eninge we ran at Indianapolis this year we used a polyol synthetic. When we tore the engine down, you could still see the original honing marks on the bearings...no wear at all. We put the same bearings back in because the crankshaft never touched the bearings. I've never seen that before."

"Another example of the capacity of synthetic oil to deliver exceptional engine protection and performance is a recently-completed demonstration involving the Amsoil Corporation of Superior, Wisconsin, a major manufacturer of a wide range of premium synthetic oils, automatic transmission fluids, chassis lubricants, and related products. This demonstration involved the use of its 100% synthetic engine oils in a New York City taxi fleet. The test, sponsored and supervised by a major lubricant additive manufacturer, compared the overall performance of Amsoil's 10W-40 synthetic oil with a number of leading petroleum motor oils. The demonstration was scheduled to encompass 60,000 miles of New York taxi service on each car. With the high levels of idling time typically encountered in such service, the total number of, "engine miles", of each car was estimated to be about double the miles registered on its odometer.

Initially the demonstration was to have required that each taxi, equipped with a Chevrolet 229 CID V-6 engine, have its oil and filter changed every 3,000 miles. But Amsoil insisted that an alteration of the test procedure be instituted. The company's intent was to push its synthetic oil to the extreme and evaluate how it compared to the petroleum oils drained at the originally specified, 3,000 mile intervals. The twelve Amsoil-lubricated vehicles were thus divided into three goups of four taxis each. Group 1, (Amsoil), would double the control interval, with oil and filter drain at 6,000 miles; Group 2, (Amsoil), would quadruple the control interval, with oil and filter drain at 12,000 miles; and group 3, (Amsoil), would not change the oil for the duration of the test ; thus multiplying the, (petroleum), Control Group's drain-control interval by twenty times. In place of changing the oil, these, (Group 3), cars would be equipped with Amsoil's By-Pass oil filter, claimed by the company to keep, (synthetic), oil analytically clean for up to 25,000 miles of driving, without replacing the element. The by-pass filter element was changed at 12,500 mile intervals for the duration of the test.

Following the year-long demonstration, each of the engines was disassembled, both to determine the levels of sludge, varnish and rust that had accumulated inside the engine, and to carefully measure the amounts of wear experienced on critical engine components. Pictured on the previous page are representative samples of various components of the test engines. In the first example, the pistons and intake valves of the petroleum Control Group, (oil and filter changes every 3,000 miles), are illustrated. The lower set of photos represent the same engine components from an Amsoil Group 3 vehicle. Note the substantially reduced varnish and sludge deposits on the synthetic-oil lubricated components, and the remarkably good overall condition of the Amsoil group 3 pistons and valves.

To summarize the findings and conclusions, the test facility responsible for the demonstration submitted this statement: "The data presented in this report indicates that the Amsoil synthetic SAE 10W-40 passenger-car motor oil formulation...provided protection of the test engines from excessive wear and deposit formation, far beyond the normal 3,000-mile oil change interval." In fact, the level of protection was such that those engines in which the original synthetic oil was run for the entire duration of the, (60,000 mile), test showed less wear than did the Control Group vehicles using premium petroleum oil and 3,000 mile drain intervals."

"Renowned race-car driver Bobby Unser stated in an article in, "The Family Handyman", magazine: "I've had tremendous success with synthetics; both grease and oil, in all my cars. In several instances where we have compared petroleum-lubricated engines with those which used synthetics, the latter were cleaner, with less carbon and sludge. And the engines produced more horsepower, which meant better mileage and longer life."

"But", you say, "if synthetics are so good, why aren't even more motorists using them?" First and foremost, many folks simply aren't aware of synthetics. Others who are aware are deterred by the higher purchase cost, without investigating the advantages. Even many professional mechanics haven't kept abreast of the advances that have occurred in the field of synthetic lubricants, and frequently tend to dismiss them without bothering to check the wealth of current literature and impressive test results regarding them. Secondly, garages and dealerships often hesitate to recommend any extended-drain lubricant, perhaps because their livelihood is to a large degree dependent upon frequent servicing and repairs. We learned of one, (probably common occurring), instance where a dealership mechanic told a customer: "You can't use synthetic oil in your car...the eninge wasn't designed for it!" Still another reason is that many of the advantages and cost savings provided by synthetic lubricants are difficult to quantify, and thus difficult for many consumers to appreciate. For instance, how does one place a precise value upon such benefits as..."cleaner engine; lower operating temperatures; fewer oil and filter changes; less oil consumption; lowered octane requirements; longer battery/starter/alternator/spark plug/turbo unit/PCV component life; increased fuel mileage; the convenience of exceptional four-season performance with a single motor oil...and so on." On the other hand, it is quite simple to compare the purchase costs of conventional vs synthetic, and to ignore the real cost-and performance comparisons in actual operation. Do you prefer to save $12 or $15 per oil change by using a petroleum oil, even knowing that it should be changed six or seven times as frequently as a premium synthetic? Or are you more interested in the bigger picture, irrespective of the fact that many of the very real benefits of synthetics cannot be precisely quantified in terms of dollars and cents? All available evidence indicates that synthetic engine oils offer performance advantages not achievable with any refined-petroleum product.

Does all of this mean that synthetic motor oils are superior to conventional petroleum oils? If you value your automobile engine and would like to keep it in peak, trouble-free operating condition year after year and far beyond its normal expected life, our conclusion is, "Yes, without question".

Where to get product
Click on this button

Order AMSOIL now using the easy application guide

Place your order immediately using the application guide. Enter your year, make and model of your vehicle. Shipping is fast and very economical.

What fits all your vehicles

Interstate Battery System of Detroit very satisfied with the results of Amsoil in their fleet!

Running a 10W30 oil for 240 hours!

AMSOIL was the first synthetic oil

Mercedes-Benz and motor oil law suits

Interceptor 2-cycle oil

Companies wanting to buy out AMSOIL

Harley-Davidson Oil. Which is better?

Regarding your factory warranty

Crackdown of obsolete oils in California

Company History

Motorcycle Fluids