Synthetic Oil: Is It Right for Your Vehicle?

Stephen Fogel
October 15, 2017

As car engines have gotten more powerful and complex, they've also gotten better at increasing fuel economy while reducing the amount of pollutants emitted.

Motor oil technology has steadily advanced along with engines. The oil industry has responded to the demands of automakers and regulators with products that can withstand the increased demands.

But there are limits to what can be achieved with conventional petroleum-based motor oils. This has led to the development of synthetic oils, which have capabilities that go way beyond those of conventional oils. Of course, these high-performing synthetic oils also cost more than conventional oils.

So, is synthetic oil right for your car? Let's look the differences between the various types of motor oil available in detail, evaluating the pros and cons of each type, and come to some conclusions about which oil may be the right one for your specific vehicle and driving situation.

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How to know if your vehicle requires synthetic oil

There are two different answers to this question, based on two different interpretations of the word “requires.” 

If your owner’s manual requires synthetic oil, you must use it

This one's easy. If your vehicle’s manufacturer says you need to use synthetic oil, you use it. While this used to apply primarily to high-performance vehicles, many more cars require synthetic oil these days.

If this applies to you, you must use synthetic oil, and stick to the prescribed intervals. Doing otherwise not only risks potential engine damage, but could also void your warranty, even if your engine problem has nothing to do with the oil. 

Symptoms from using the incorrect oil include: 

There are other reasons why synthetic oil may be required

This relates to the conditions you drive in regularly, the vehicle you drive, and your long-term plan for that car. If you deal with any of the following conditions, synthetic might be necessary or at least ideal:

  • You drive in extreme heat, extreme cold or dusty conditions
  • You have a high-performance vehicle
  • You have an engine with a turbocharger or supercharger
  • You tow heavy loads
  • You go longer than you should between oil change intervals (this can void your warranty)
  • You plan to keep your car for a long time
  • You make lots of short trips

On the other hand, conventional oil is fine in the following cases, assuming your owner's manual says it's OK:

  • You live in a moderate climate (not too hot and not too cold)
  • You change your oil according to the manufacturer’s service schedule
  • You lease your vehicle
  • You get a new car every few years
  • You have an older car that uses or burns a significant amount of oil (regularly topping up with synthetic gets expensive)

Is synthetic oil right for you?

Synthetic oil is a much better product than conventional oil. It performs better, lasts longer, protects your engine better, reduces friction for better fuel economy, and flows better when cold. Synthetic oil has been thoroughly tested and proven, so you can use it with confidence.

Unfortunately, it's also expensive.

If you don't want to spring for the cost of synthetic, but want more protection than conventional oils provide, a synthetic blend is an acceptable middle ground.

If you lease or buy new cars frequently, and rarely drive in extreme weather, then conventional oil with normal change intervals should be just fine.

Whatever oil you choose, please remember to change it and the filter regularly, based on the recommendations in your owner’s manual.

Let's look closer at how your oil works, and what the differences are between synthetic, conventional and blends.

The role of motor oil in your vehicle’s engine

The oil that circulates through your engine has several important functions:

  • Keeping the moving parts from touching
  • Reducing friction
  • Transferring heat away
  • Carrying away contaminants and debris
  • Protecting against wear
  • Preventing corrosion

Today’s oils are a chemically complex blend of about 80% base oil stock (for essential lubrication functions) and 20% additives. These additives help the oil last longer, flow better and survive harsh conditions.

What is synthetic oil?

Synthetic oil is made of artificially made chemical compounds. These compounds can be derived from petroleum products, or they can be made from other raw chemical materials. What they have in common is a higher level of performance compared to conventional oils. Synthetic oils are specifically adapted to operate in situations beyond the limits of conventional oils.

In addition to being refined, just as conventional oil is, synthetic oil is also purified, distilled and reduced to its basic molecular building blocks. This eliminates many of the impurities that remain in conventional oil. It also allows these individual molecules to be “customized” for the demands of today’s engines. These molecules can now better protect your engine and maximize its performance. This is called the “base stock.”

Next comes the special package of additives — an essential part of synthetic oil. These additives are usually of superior quality, and work even better because of the synthetic oil’s custom-built base stock structure. Engines typically run cleaner and smoother with synthetic oil in the crankcase.

The benefits of using synthetic oil

There are many benefits of using synthetic motor oil. Synthetic oil does all this:

  • Reduces wear when the engine is cold
  • Flows and lubricates better at low temperatures
  • Resists thinning at high temperatures
  • Improved resistance to oxidation, sludge and breakdown
  • Lasts longer
  • Improves fuel efficiency
  • Improves protection from deposits and ash formation in turbocharged and supercharged engines
  • Allows for more horsepower and torque due to less friction and drag in engine
  • Creates a higher safety margin in extreme conditions (very high or low temperatures, letting oil level get too low, etc.)

Synthetic oil vs. conventional oil

Synthetic oil runs rings around conventional oil in terms of performance. A recent AAA research study found that synthetic oils protect engines an average of 47% better than conventional oil. They're more stable, flow better at low temperatures, their additives last longer, and they reduce engine wear more. So if performance is your only concern, definitely choose the synthetic.

But there's the cost issue.

This is the primary problem for budget-conscious drivers. Synthetic oil costs more than conventional oil, approximately twice as much. Is it worth it?

Strictly speaking, it is. Synthetic oil is a superior product. It will do a better job over a wider range of conditions than conventional oil. It's also a much more complex product to make, so that contributes to its increased cost. You get what you pay for, and all vehicles will benefit from it. That AAA research study estimated the increased price of using synthetic oil came out to $5.33 per month. Considering how much an engine problem would cost, that could be a bargain.

Synthetic blend oil vs. full synthetic

There is a middle ground. By creating a new type of oil that's part conventional and part synthetic, and splitting the cost difference, we now have a good-better-best lineup of oils on the shelf. Synthetic blends sit in the middle of the rather large price gap between conventional and synthetic oils.

When does a synthetic blend make sense? It’s really a judgment call on your part. If you absolutely refuse to spend what a full synthetic costs, but still feel that you need more protection than conventional oil offers, then a synthetic blend makes sense.

One final tip to keep in mind: if your owner’s manual specifies that full synthetic oil is required in your vehicle, DO NOT substitute synthetic blend oil. This will void your warranty.

Synthetic oil changes vs. regular oil changes

During an oil change, the old oil in your engine is drained out and replaced with new oil. Your old oil filter is also removed and replaced with a new one. Whether you are using conventional oil or synthetic, the process, and the amount of labor involved, is the same.

The only difference is the type of oil and its cost. Synthetic oil costs more, so a synthetic oil change will cost more than a conventional oil change. 

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Oil change intervals should be the same, regardless of the type of oil. Check your owner’s manual. If you do a lot of stop-and-go driving, you should observe the manufacturer’s “severe service schedule,” which typically specifies more frequent changes.

About extended oil change intervals

Some synthetic oil makers may tout longer oil change intervals, and some higher-end synthetic oils are sold with that promise. Extending your oil change intervals with synthetic oil will effectively reduce the cost of your oil changes on a cost-per-mile basis. But it’s not that easy.

If your car is under warranty, you must observe the manufacturer’s oil change intervals, whatever oil you use. Otherwise you will void your warranty. Regardless of how long the oil itself claims to hold up, it's constantly being contaminated with the byproducts of combustion. These accumulate at the same rate, no matter which oil you use. Changing the oil removes these contaminants, so the longer they stay in your oil, the more damage they can do.

Stephen Fogel

About the Author

Stephen has been an automotive enthusiast since childhood, owning some of his vehicles for as long as 40 years, and has raced open-wheel formula cars. He follows and writes about the global automotive industry, with an eye on the latest vehicle technologies.

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