Synthetic oil

Synthetic oil, once found mostly in high-performance cars, is being used in more mainstream vehicles.

Take, for example, the popular Honda Civic. A Honda spokeswoman said the automaker uses a synthetic oil in the Civic for its low viscosity—meaning it flows more easily than oils with higher viscosity—which helps to improve the engine's fuel efficiency. The faster the oil flows, the quicker the engine parts can turn.

Car Maintenance

Honda is not alone, says Mel Yu, auto analyst at Consumer Reports. In the 2019 model year, about 70 percent of new cars get either fully synthetic or blended oil.

Several brands, including Honda, don't specifically require synthetics for their engines, but the low-viscosity oils that those engines need are offered only in a synthetic format, Yu says. Some brands use “synthetic blend” oil, which is a combination of conventional and synthetic oils. Blends don’t deliver the full benefits of synthetic, but they’re considerably cheaper, he adds.

On top of that, many oil-change outlets also offer synthetic oil as an alternative to conventional engine oil.

According to Will Hixson, spokesman for the Automotive Oil Change Association, the 2018 National Oil and Lube News annual survey shows that more than half of car owners are choosing synthetics or synthetic blends when they get their oil changed.

Type of Oil

Percentage of Oil Changes Performed

Semi-synthetic (or blend) oil

35

Conventional oil

32

Full synthetic22
High-mileage oil6
Diesel5

Should you use synthetic oil? There are good reasons to—but only if your car has specific needs.

Synthetics have some advantages over conventional motor oil. They’re designed to be more effective at:

  • Resisting oil breakdown, which makes it last longer than conventional oil
  • Withstanding higher temperatures than conventional oil, which helps keep engines running longer
  • Flowing in cold temperatures, thus reducing engine wear during frigid startups.

There's a downside: Synthetic motor oil can cost two to four times as much as regular oil. So unless your owner's manual specifies synthetic, you don’t need it.

But John Ibbotson, Consumer Reports’ chief mechanic, says there are some situations where synthetic oil’s resistance to breakdown (the tendency of oil to degrade and lose its viscosity over time) can help prolong the life of an engine:

  • If you make lots of short trips, standard motor oil may never get warm enough to burn off moisture and impurities that can accumulate. That could hasten the breakdown of conventional oil.
  • If you live in a region with very cold winters or very hot summers, or if you use your vehicle for towing or hauling heavy material, synthetic oil helps protect the engine from strain and won’t break down as quickly as conventional oil.
  • If you have an older engine that’s prone to sludge buildup. This gunky residue forms when oil breaks down, and it can block oil passages and lead to a quick engine death. In the early 2000s, several engines from Chrysler, Toyota, and Volkswagen, among others, were especially prone to sludge buildup. Synthetic oil is less likely to form this troublesome sludge.

Though synthetics generally hold up better for more miles, regular oil changes remain important, and you shouldn’t wait beyond the time interval recommended by the manufacturer—typically every six months or a year.

Using synthetic in these situations will prolong your oil life and require fewer changes. That’s also a major benefit to the environment, as used motor oil is a major source of toxic waste in water. 

Oil change with synthetic oil.
Certified mechanic Chris Jones checks oil levels at the CR Auto Test Center.