AAA study: Synthetic oil better than conventional

ORLANDO, Fla. — Synthetic motor oil outperformed conventional oil by an average of nearly 50 percent, according to a new evaluation by AAA Inc., which concluded that synthetic oil offered "significantly" better engine protection for only $5 more per month when following a factory-recommended oil change schedule.

Based on its study, AAA — which provides more than 57 million members with travel, insurance, financial and automotive-related services — recommended that vehicle owners consider a switch to synthetic oil at their next oil change service.

"Oil protects critical engine components from damage and AAA found that synthetic engine oils performed an average of 47-percent better than conventional oils in a variety of industry-standard tests," said John Nielsen, AAA's managing director of automotive engineering and repair.

"With its superior resistance to deterioration," AAA's findings indicate, "synthetic oil is particularly beneficial to newer vehicles with turbo-charged engines and for vehicles that frequently drive in stop-and-go traffic, tow heavy loads or operate in extreme hot or cold conditions."

Synthetic base oils offer various performance benefits, such as high-temperature stability, high film strength and a naturally high viscosity index. These characteristics are beneficial for engines that tend to operate at higher RPMs and temperatures, AAA said.

Semi-synthetic blends were not evaluated in the study.

Acknowledging that only a limited number of newer vehicles specifically require synthetic oil, AAA said all vehicles can benefit from using synthetic oil.

Consumer reluctance

However, in a companion AAA nationwide survey of U.S. drivers, 44 percent are either unsure (27 percent) or do not believe (17 percent) that the more expensive synthetic oil is better for a vehicle's engine.

Reasons cited for choosing the cheaper, conventional oil include feeling that synthetic oil is too expensive, offers no benefit, that the upgrade to synthetic oil is an unnecessary up-sell by a repair facility or they are simply not offered the choice, according to AAA.

The association estimated that switching to a synthetic oil from a conventional one will cost the average driver $64 more per year, or an extra $5.33 per month.

In a survey of AAA's Approved Auto Repair facilities, the average cost of a a synthetic oil change is $70, or nearly twice the $38 charged for a conventional oil change. For those who change their vehicle's oil themselves, the average cost of five quarts of synthetic oil is $45, vs. approximately $28 for conventional oil.

"It's understandable that drivers may be skeptical of any service that is nearly twice the cost of the alternative," Mr. Nielsen said. "While a manufacturer-approved conventional oil will not harm a vehicle's engine, the extra $30 per oil change could actually save money in the long run by protecting critical engine components over time."

The hesitation to select a synthetic oil may stem from consumers' distrust in repair facilities, according to AAA. In another of its surveys, the association concluded that two-thirds of U.S. drivers do not trust repair facilities, with most citing concern over the recommendation of unnecessary services.

Oil study

AAA's engine oil study focused on eight industry-standard ASTM (American Society for Testing and Materials) tests to evaluate the quality of both synthetic and conventional engine oils in terms of shear stability, deposit formation, volatility, cold-temperature pumpability, oxidation resistance and oxidation-induced rheological changes.

AAA said it contracted with two independent (International Standards Organization) ISO 17025-certified testing labs to perform the ASTM International standard tests. All tests, with the exception of ASTM D7528, were performed twice on the same test oil and averaged.

AAA said it purchased five randomly selected oil brands from Orlando-area auto part retailers. Only brands that produced both conventional and full synthetic oils were considered.

At the time of testing, all tested oils were licensed by the American Petroleum Institute and advertised to meet the International Lubricants Standardization and Approval Committee's GF-5 specifications, according to AAA.

An SAE 5W-20 conventional and synthetic oil from each of the five selected brands was sourced for evaluation because this viscosity is common in newer vehicles, AAA said, noting that low viscosity oils will be increasingly popular in the future.

When the percent differences across each conducted test were combined and averaged (equal weight was given to each test), synthetic oils outperformed conventional oils in the conducted tests by 47 percent, AAA said.

It concluded that a synthetic oil may provide more protection in extreme operating environments or provide some additional protection in cases where manufacturer specified oil change intervals are not closely followed by the consumer.

Additionally, the test results suggest that use of a synthetic oil may result in less engine wear over the life of the vehicle.

OEM specs

AAA noted that it found only two low-volume, high-performance vehicles that specify synthetic oil as required. However, the majority of vehicle manufacturers require compliance to an internal specification for warranty purposes.

Most vehicle manufacturers regard their internal oil specifications as proprietary; however, it is possible to determine what oils meet the specification, according to AAA.

Of the three manufacturers AAA studied, two required adherence to an internal specification. These specifications included dozens of motor oils, the majority of which were classified as a full synthetic. The remaining oils were classified as a "synthetic blend."

The third manufacturer recommended use of its licensed oil; however, oils meeting ILSAC GF-5 and API SN specifications are permissible for use if they are of the recommended viscosity for the specific vehicle, according to the report.

AAA concluded that consumers should consult their vehicle owner's manuals to determine what, if any, manufacturer specification is required.

Consumer study

In a separate survey of consumer trends, AAA contracted with a national research company to conduct a telephone survey of 1,007 adults living in the U.S.

About 45 percent of the respondents said they typically use synthetic motor oil for their vehicle, while 30 percent typically use conventional motor oil and 3 percent typically use some other type of oil. Another 22 percent were unsure what type of motor oil is used for oil changes on their vehicle.

About 56 percent of the respondents said they believed synthetic motor oil is better for their engines vs. 17 percent who do not and 27 percent who weren't sure.

Among respondents who typically use conventional motor oil in their vehicles, 43 percent said their choice was due to synthetic motor oil being too expensive. Other reasons included not usually being offered a choice of motor oil when getting an oil change, not thinking that synthetic motor oil is any better than conventional oil, and a belief that shops offering synthetic oil are just trying to sell something they don't need.

AAA's full research report, fact sheet and additional supporting materials can be found at NewsRoom.AAA.com.