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Synthetic or Conventional Motor Oil - Fact Or Fiction

Luke Munnell
Jul 1, 2008
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We've all heard the endless arguments in favor of synthetic motor oils over petroleum-based alternatives, and we're all too familiar with retorts made in defense of the conventional dinosaur juice. Debates rage on, new arguments are made-and countered-and both forms of the slippery stuff are still bought, used, and defended by gearheads everywhere. What we're concerned is very simple: Can popular synthetic oils that promise to improve power over similarly rated conventional oils really deliver?

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In theory, the molecules of synthetic oil bases can be manufactured to offer better lubrication without increasing viscosity-meaning a 30-weight synthetic oil will supposedly decrease friction better than a 30-weight conventional oil, reducing parasitic loss inherent in an engine's moving parts, improving overall efficiency, and transferring more power to a car's wheels. To test the claim, we headed to Westminster, Calif., and strapped our Project DC2 to the rollers of MD Automotive's Dynojet dynamometer four times over; each time we filled our car with a different 5W-30 conventional or synthetic motor oil.

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The Verdit: The synthetics made power-up to 2.2 hp in our tests-and they did it by improving overall efficiency, which means better fuel economy to boot. And if efficiency is improved by reducing friction, they'll likely increase engine longevity. Granted, the improvements made here aren't huge, but neither are the demands put forth by our DC2's low-revving, naturally aspirated 1.8L four-banger. Engines with more moving parts, or bigger displacements, will benefit proportionately from the decreased frictional resistance offered by these oils, and the powerbands of higher-revving engines approaching redline will likely benefit exponentially.

Next Month
Coolant additives-do they keep you cool, or make you a fool?

Got a debate for us? Throw an e-mail to:


MD Automotive
Westminster, CA 92683
By Luke Munnell
304 Articles



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