Synthetic lubricants are fuel-efficient, extended-life lubricants manufactured from select base stocks and special-purpose additives. In contrast to petroleum oils that are pumped from the earth and refined, synthetics are custom designed in the laboratory, with each phase of their molecular construction programmed to produce, in effect, the ideal lubricant.

Many people with questions about synthetics haven't known where to get correct information. Some enthusiasts swear that synthetics are capable of raising your tractor, baler or combine from the dead. On the other hand, the next fellow asserts that synthetics will send your beloved John Deere to an early grave.

Where's the truth in all this?

In an effort to set the record straight, we've collected eight persistent myths about synthetic motor oils to see how they stack up against the facts.

Myth #1: Synthetic motor oils damage seals. Untrue. It would be foolhardy for lubricant manufacturers to build a product that is incompatible with seals. The composition of seals presents problems that both petroleum oils and synthetics must overcome. Made from elastomers, seals are inherently difficult to standardize.

Ultimately, it is the additive mix in oil that counts. Additives to control seal swell, shrinkage and hardening are required, whether it be a synthetic or petroleum product that is being produced.

Myth #2: Synthetics are too thin to stay in the engine. Untrue. For a lubricant to be classified in any SAE grade (10W-30, 10W-40, etc.), it must meet certain guidelines with regard to viscosity.

For example, it makes no difference whether it's 10W-40 petroleum or 10W-40 synthetic, at -25°C (-13°F) and 100°C (212°F) the oil has to maintain a standardized viscosity or it can't be rated a 10W-40.

Myth #3: Synthetics cause equipment to use more oil. Untrue. Synthetic motor oils are intended for use in mechanically sound engines — that is, engines that don't leak. In such engines, oil consumption will actually be reduced, because of synthetic lubricants' lower volatility, their better sealing characteristics between piston rings and cylinder walls, and their superior oxidation stability (their resistance to reaction with oxygen at high temperatures).

Myth #4: Synthetic lubricants are not compatible with petroleum. Untrue. The synthesized hydrocarbons, polyalphaolefins, diesters and other materials that form the base stocks of high-quality, name-brand synthetics are fully compatible with petroleum oils. In the old days, some companies used ingredients that were not compatible. As a result, manufacturers of quality synthetic lubricants were tarred with the same brush. Fortunately, those days are long gone.

Compatibility is something to keep in mind, however, whether using petroleum oils or synthetics. It is usually best to use the same oil for topping off the oil you have been running in an engine. It is preferable not to mix your oils, because the functions of additives blended for specific characteristics can be offset when oils with different additive packages are put together. For optimal performance, it is better to use the same oil throughout.

In addition, not all greases are compatible. Some greases have a significant adverse effect on other grease formulations, and a careful evaluation should be made when changing from one grease family to another.

Myth #5: Synthetic lubricants are not readily available. Untrue. This may have been the case two decades ago when Amsoil and Mobil 1 were the only real synthetic motor oil choices, but today nearly every major oil company has added a synthetic product to its lines. This in itself is a testament to the value synthetics offer.

Myth #6: Synthetic lubricants produce sludge. Untrue. Synthetic motor oils are more sludge resistant than their petroleum counterparts, resisting the effects of high temperature and oxidation. In the presence of high temperatures, two things can happen. First, an oil's lighter ingredients can boil off, making the oil thicker. Second, many of the complex chemicals found naturally in petroleum base stocks begin to react with each other, forming sludges, gums and varnishes. One result is a loss of fluidity at low temperatures, slowing the timely flow of oil to the engine for vital component protection.

Further negative effects of thickened oil include the restriction of oil flow into critical areas, greater wear, and loss of fuel economy.

Because of their higher flash points and their ability to withstand evaporation loss and oxidation, better synthetics are much more resistant to sludge development.

Two other causes of sludge — ingested dirt and engine coolant dilution — can be a problem in any kind of oil, whether petroleum or synthetic. These are problems with the air filtration system and the cooling system, respectively, not the oil.

Myth #7: Synthetics last forever. Untrue. Synthetic base stocks cannot be used forever; eventually the additives will be depleted and cause the oil to require recharging. Moisture, fuel dilution, acids, and, in the case of petroleum oil, oil degradation tend to use up additives in an oil.

However, through “topping off,” additives can be replenished. Through good filtration and periodic oil analysis, synthetic engine oils protect an engine far longer than non-synthetics can.

Myth #8: Synthetics are too expensive. Untrue. Tests and experience have proven that synthetics can greatly extend drain intervals, provide better fuel economy, reduce engine wear and enable vehicles to operate with greater reliability. These benefits more than offset initial price differences.

In farming it is extremely important to be able to operate one's equipment continuously during peak seasons. Taking time to change oil can jeopardize production. With extended drains, oil changes can be scheduled during the off season, thereby maximizing productivity.

Ed Newman is the marketing and advertising coordinator for Amsoil Inc., Superior, WI.