Common myths surrounding synthetic motor oils.

With so many myths surrounding synthetic motor oils, the saying, “a little knowledge is dangerous” comes to mind. From the extremes of wild claims of indestructible properties to the myths that synthetic oils are not compatible with certain petrols, synthetic engine oils elicit a lot of discussion.

Understanding where the myths surrounding synthetic motor oils come from.

Synthetic motor oils are fuel efficient lubricants manufactured from select base stocks and special purpose additives which extend the oil’s life. Synthetic oil base stocks are made from organic compounds or synthetic hydrocarbons using a process that re-arranges the structure so all the molecules are uniform in size, shape and weight, a phenomenon that does not occur in nature.

In contrast to petroleum oils which are pumped from the earth and refined, synthetics are custom-designed to produce, in effect, the ideal lubricant.

Right here is where one of the greatest myths surrounding synthetic motor oils is born: Certain mineral oils are also classified as synthetic motor oil!

What are the most common myths surrounding synthetic motor oils?

Are synthetic oils super oils... or snake oils? Some enthusiasts will swear that synthetics are capable of raising your car from the dead. On the other hand, the next fellow asserts that they’ll send your beloved car to an early grave.


Synthetic motor oils can't be used with catalytic converters or oxygen sensors. 

Untrue! This is one of the myths surrounding synthetic motor oils There is no difference between synthetic and petroleum oils in regards to these components. Both synthetic and petroleum motor oils are similar compounds and neither will damage catalytic converters or oxygen sensors. In fact, because engines tend to run cleaner with synthetics, sensors and emission control systems run more efficiently and with less contamination.

It’s actually the zinc additives in older oils that are incompatible with the catalyst.

Synthetic engine oils cause cars to use more oil. 

More myths surrounding synthetic motor oils! 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. Firstly, because of the lower volatility of synlubes. Secondly, because of the better sealing characteristics between piston rings and cylinder walls. And finally, because of the superior oxidation stability (i.e. resistance of synthetics to react with oxygen at high temperatures.) 

Synthetic engine lubricants produce black sludge. 

And so the myths surrounding synthetic motor oils grow! In point of fact, synthetic motor oils are more sludge resistant than their regular 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 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 sludge, gum and varnish. 

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, synthetic oils are much more resistant to black sludge development, destroying one of the myths surrounding synthetic motor oils.

Two other causes of sludge; ingested dirt and water 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.

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

And so the myths surrounding synthetic motor oils continue!

Synthetic motor oils leak because they’re too thin to stay in the engine. 

One of the most widely quoted myths surrounding synthetic motor oils. In order for any lubricant to be classified in any SAE grade (10W-30, 10W-40, etc.) it has to 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 degrees centigrade and 100 degrees centigrade the oil has to maintain a standardized viscosity or it can't be rated a 10W-40.

Synthetics last forever.

Untrue. These myths surrounding synthetic motor oils are given credence by some “experts” who feel that synthetic base stocks themselves can be used forever. It is a well-known fact that eventually the additives will falter and cause the oil to require changing. Moisture, fuel dilution, and the by-products of combustion (acids and soot) tend to use up additives in an oil, allowing degradation to occur. 

However, by "topping up", additives can be replenished. Through good filtration and periodic oil analysis, synthetic engine oils protect an engine for lengths of time far beyond the capability of non-synthetics.

Synthetic motor oils are too expensive. 

Superficial analysis to these myths surrounding synthetic motor oils: Tests and experience have proven that synthetics can greatly extend engine oil change intervals, provide better fuel economy, reduce engine wear and enable vehicles to operate with greater reliability. This more than offsets initial price differences. All these elements combine to make synthetic engine oils more economical than conventional non-synthetics.

In Europe, synthetics have enjoyed increasing acceptance as car buyers look first to performance and long term value rather than initial price. As more sophisticated technology places greater demands on today's motor oils, we will no doubt see an increasing re-evaluation of oil buying habits in this country as well.

Now that the myths surrounding synthetic motor oils have been debunked: