Synthetic or Conventional Oil?

Breaking down a slippery subject
on

Traditional wisdom tells us that a synthetic creation is usually not quite as good as the original it strives to emulate. (The difference between clothing made of polyester versus silk comes to mind.) Does that same truism apply to synthetic oil, when compared to automotive oil derived from crude?

Fundamentals

To grasp this slippery subject, we first need to cover some fundamentals. Synthetic oils are a result of scientific manipulation of non-conventional fluids, but here the silk-or-polyester analogy stops. Synthetic oils are definitely not the equivalent of polyester leisure suits; in fact, they are generally priced three to four times that of conventional oil. And, more to the point, synthetics are an improvement over their conventional kin.

Let's break down the details of synthetics, and what makes them better. One definition of "synthetic" is big molecules built up from small ones. Like genetic engineers, the oil companies figured they could improve the performance of engine oil and eliminate some of the shortcomings in the laboratory.

In the simplest terms, the base stock of synthetics, polyalphaolefin (PAO) starts as ethylene gas, a simple two-carbon molecule that is built up to a 10-carbon molecule. Three of these super molecules are combined to form PAO, a base stock that offers a number of advantages over Mother Nature's version. Synthetics are more stable, flow at lower temperatures, are more resistant to boiling off, and less susceptible to oxidation, which causes thickening with prolonged high temperatures.

The inherent element with crude stock for motor oil is the molecular construction. Conventional motor oil is a batch of short-chain and long-chair carbon and hydrogen atoms. In extreme heat, the short chains can evaporate and these unstable molecules oxidize and break down. In addition, contaminants and reactive and/or unstable hydrocarbons can sneak through the refining process.

What's It Worth?

Are synthetics worth the extra cost? Universally, the answer is yes, whether for a high-revving turbo motor or an older engine that gets little use. Using another vivid comparison, French champagne is also worth the extra expense over sparkling wine, but it comes down to matters of your taste and bank account. Note, too, that most auto manufacturers do not specify synthetics, so unless you're one of the few who need synthetic oil, rest assured that you're doing no harm with good old-fashioned crude as long as you follow the owner's manual recommendations on viscosity and grade.

On the other hand, synthetics are better on a number of levels. They keep the engine cleaner through improved sludge and varnish protection, reduce engine wear at high temperatures with more stable viscosity, protect the engine when it's running under severe conditions at high temperatures, provide better cold-temperature starts with faster oil flow at ignition and improve fuel efficiency.

Myths

As with any new technology, there are a number of myths and advertising claims that need to be explored. Back in the late 1990s, the National Advertising Division (NAD) of the Council of Better Business Bureaus ruled that "synthetic" could be defined as the product of an intended chemical reaction.

As a result of this battle of semantics, the NAD, the Society of Automotive Engineers and the American Petroleum Institute ended up with broad interpretations of "synthetic." What that means to the layperson is this: if you want full synthetic or semi-synthetic or whatever, read the label to make sure you're getting what you want and what you think you're paying for.

One urban myth surrounding synthetic oil is its compatibility with conventional oil. At one time, those who switched from conventional to synthetics had to stick with synthetics-there was no going back. Synthetics expanded the seals in the engine; then, when conventional motor oil was used, that engine sprang multiple leaks.

Usage

Now, while the companies don't recommend mixing or switching back and forth, one company's synthetics are fully compatible with others and compatible with conventional oils. The source of compatibility problems was high levels of ester in the earlier synthetics. Considering the consequences, it's best to verify this compatibility, either on the company's website or with your trusted mechanic.

Next, oil changes. The PAO base stock does hold up longer than petroleum-based oils, but the additives in both wear out at the same rate. The oil companies have tested their synthetics for longevity, but they still recommend following the specific owner's manual for oil change intervals.

As for special oil filters or special disposal techniques for those who change their own oil, that's easy. You can use the same filter and follow the same disposal procedures that you would with conventional oils.

So, should you bite the bullet and fork over more money for synthetics? Sure, if you want to. If you are in a fully committed relationship with the car of your dreams, and have decided that car is worth the cost, spring for that Dom Perignon.

Afraid of paying too much?
Get price quotes from dealers
near you... get ready to SAVE!

Get Internet Price