Americans are wary of claims from automakers and mechanics regarding the kind of motor oil to use in their vehicles. Some two-thirds do not trust repair facilities, fearing that recommended services may be unnecessary.

According to AAA, however, one thing U.S. drivers can be confident of is a recommendation to use synthetic (sometimes called “full synthetic”) oil. The association found that synthetic oil outperformed conventional oil by an average of 50% in a recent, independent evaluation when motorists follow the factory-recommended oil change schedule.

The additional cost to switch from a conventional oil to a synthetic will cost about $5 more per month, according to AAA. The average cost of a conventional oil change is $38 for five quarts of oil, compared to a cost of $70 for switching to synthetic oil.

AAA’s managing director of automotive engineering and repair, John Nielsen, said:

With its superior resistance to deterioration, AAA’s findings indicate that 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. … It’s understandable that drivers may be skeptical of any service that is nearly twice the cost of the alternative. 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.

In its survey, AAA found that 30% of U.S. drivers use conventional oil, 45% use synthetic oil, and the remaining 25% have no idea what kind of oil is in their vehicle. Some 44% either do not believe that synthetic oil is better for their vehicle (17%) or don’t know which type of oil is better (27%).

AAA’s engine oil research 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.

The full report from AAA is available here and the Association has also published a fact sheet for those of us who prefer to skip the technical details.

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