Sythetics: The Auto Industry's Best-Kept Secret
Getting the most out of your 5.0 starts by using the best oil.

Muscle Mustangs & Fast Fords - May 1992
by John Hunkins

Have you ever heard the story about the light bulb that doesn't burn out or the razor blade that never dulls? Sure, these stories get exaggerated, but sometimes there's an element of truth to the rumors leaking out of a manufacturer's skunkworks. One particular rumor that sounds too good to be true is "an experimental motor oil that increases horsepower, practically stops engine wear in its tracks and improves fuel efficiency."

Well, synthetic motor oil is not a rumor. It's been in use ever since World War II (the Germans used it on the cold eastern front because conventional oil wouldn't flow in the arctic-like weather). Even though it sounds too good to be true, synthetics do reduce engine wear, improve gas mileage and, most important for us gearheads, increase horsepower. This is because synthetic oil molecules are superior in a number of ways to their mineral-based brethren.

To spare you the technical jargon, we'll just say that synthetics have a higher resistance to heat than mineral-based oils. Because synthetic oil is composed of molecules that are uniform in weight and shape, its heat of vaporization is much higher (more than 600 degrees F. compared to conventional oil, which begins evaporating at temperatures as low as 350 degrees F.). This added stability at high temperature means that your hard-working 302 HO won't burn up as much oil-and that means less sludge and fewer varnish deposits inside the engine.

Added slipperiness is another attribute of synthetics. The uniform length of synthetic oil polymers allows them to more easily slide over one another. The resultant reduction of friction shows up as more horsepower at the flywheel. What you do with it is up to you; you can reduce throttle ~ pressure and save at the gas pump, or shave a tenth off your ET.

Higher film strength. however, is the real mother lode of synthetics. Film strength is what keeps oil molecules from being pushed away from each other under pressure. Mineral-based oil has a film strength of about 500 psi, while synthetics are closer to 3000 psi. In an area where two metal surfaces meet, the film of oil between them prevents them from rubbing and wearing away at each other. Synthetics do a better job of this than conventional mineral oils. (Remember, it takes six times as much pressure to squeeze synthetic oil from between two surfaces than conventional oil.) Consequently, synthetics are much better at keeping your engine like new.

All this boils down to one thing: It makes more sense to buy a $5 quart of oil than a $1900 engine rebuild.

Film strength is important in another way - cold start protection. Regular mineral-based oil will not remain as a boundary layer (a uniformly thin coating) on metal surfaces when an engine is turned off. Mineral oil drains oft parts and out of passageways into the oil pan. No big deal-until you crank your stallion and go hoofing into the sunset. There are some mighty important metal surfaces crying out for lubrication in the time it takes for your oil pump to fully pressurize all of those bearings, lifters and passageways. Synthetic motor oil, on the other hand, will stay on engine parts and coat them uniformly because of its high film strength and greater heat affinity (it adheres better to hot metal parts). Also, because of its higher heat of vaporization (reduced volatility), the synthetic can stave off engine wear when your engine is basically running with no oil (which can be as long as 30 seconds after cranking the motor). Wouldn't it be nice to have a strong-running mill after 100,000 miles instead of a used-up chunk of iron?

As an extra benefit, synthetics have a longer drain interval than mineral oils. The added cost of synthetic oil is offset by the need to change it less frequently. The environmental dividend is that you don't generate as much waste oil (a toxic waste) over the lifetime of the vehicle. On this note, please remember to dispose of waste oil properly. If you change it yourself, bring it to a reclamation center or a garage (which should have a large waste oil tank for reclamation).

Okay. Synthetics are great. The real question is: Why doesn't everybody use them? Automakers don't use synthetics in production vehicles, they want to sell you a new car every five years and synthetic motor oil would significantly reduce their chances of doing that. Also, the maintenance intervals can be greatly reduced.

Major racing teams don't appear to use synthetics, but things aren't always what they seem. The racing team's sponsor might want you to believe there's a certain kind of motor oil in the race car's crankcase, but the majority of successful race efforts use synthetic lubricants throughout the car.

Most big oil companies do not market synthetic lubricants because of the tremendous cost involved. The manufacture of synthetic hydrocarbons requires a totally different technology than the refining process widely in use. (This is about to change as several large oil companies are jumping onto the synthetic bandwagon, but until products are officially introduced, expect the facts to remain obscured.) Understandably, major oil companies want to sell you their product.

Interestingly enough, the biggest reason that synthetic lubricants are not in widespread use is because the would-be consumer is ignorant of the benefits provided by synthetics. Even though people have known about them for years, consumers continue to be brand- and price-driven. The rationale continues to be, "My grandpappy used brand V in his model T, so I won't use nothing else." Or, "I been usin' brand Q in my IROC for years. If I change brands now, it'll blow the motor." Or, "I ain't payin' no five dollars a quart, no sirree, Bob, I ain't that stupid." (We'll see who's stupid at the ol' Chrondeks!)

As you can see, for various reasons, people don't use synthetic motor oil (and if you use it, you'll be glad that the guy in the other lane doesn't). However, most people don't drive fuel-injected, roller-cammed, heavy-breathing, high-output, hyperactive Henrys

The topic of oil consumption should not be strange to the owners of late-model 5.Os. For years, the engineers at Ford have used low-retention oil rings in High Output 302s. Low-retention oil rings reduce cylinder friction considerably. This increases power and prolongs engine life. It also increases oil consumption. This is because the oil rings used in recent 5.Os allow more blowby than in other 302s. Synthetic motor oils can reduce the rate of oil consumption in high-output Windsors (302, 351) because they have a higher film strength. However, even synthetics cannot totally eliminate oil blowby.

When switching to a synthetic motor oil, it is important to keep several things in mind regarding oil consumption. Have an extra quart of your synthetic handy. Although many synthetic oil manufacturers tout the compatibility of their oils with mineral-based fluids, adding mineral oil to synthetic oil will drastically reduce the mileage to your next oil change (remember, synthetics last longer).

Also, as the mineral oil breaks down, it will pollute the rest of the oil, leaving sludge and varnish deposits in the engine (this is because mineral oil is made up of many chemically dissimilar hydrocarbons, including waxes, all of which react differently under various conditions). By adding a mineral oil to synthetic oil, you may also see a reduction of engine efficiency, depending on how much, and when, the mineral-based oil was introduced.

There are a growing number of companies that currently offer synthetics. Because this overview is intended to give readers a general idea of the benefits of synthetic lubricants, we have not discussed the specific differences between individual brands and their unique formulations. Keep in mind that there are differences between brands of synthetics, which may affect the performance of your engine.

There is nothing secret about the benefits of synthetic lubricants. They are for real, and I can personally testify to their effectiveness in my daily driver/drag car). The added benefits of synthetics are so great that the extra cost is almost incidental.