Can an Oil Viscosity Affect Power? We Test Idemitsu Zepro Eco Medalist 0W20 to Find Out!

Can you make significant power gains just by changing oil?  In the past, we have proven that switching from a lower grade mineral oil to a premium synthetic oil can be good for a couple or three hp. However, is it possible to make serious gains in power from just an oil change by changing the viscosity of the oil as well as the type?

We set out to experiment and find out.  Our subject in this test was our Project EP3 Civic Si.  We are currently using this car as our company get around mobile and it sees duty as a commuter and parts runner.  Project Si is currently powered by a stock K20A3 engine and we figured it would make a perfect candidate to test low viscosity and low friction oils since it was designed to run them.

Our super low friction oil is Idemitsu ZEPRO 0W-20. This blend of energy saving Idemitsu oil is fortified with Molybdenum which protects against wear. Idemitsu is factory fill on Honda’s and many other Japanese base cars so if you have not heard of the brand, be assured that its good stuff.

The formulation of ZEPRO 0W-20 was developed for cars using stop-start fuel-saving technology, the feature that shuts engines off at lights to save gas. Since most of a street car’s engine wear occurs during starting when the engine is cranked and run for a small bit of time with zero to little oil pressure, engines with this feature need more film protection against wear.

For our performance purposes, we figured that the moly that was intended to work well for continuous starting and stopping would provide extra protection against wear for driving hard! ZEPRO 0W-20 is a high quality synthetic oil that in addition to the moly, has special friction modifiers as well as traditional extreme pressure additives to deliver ultra-low viscous and mechanical friction.

Since the 0W-20 viscosity rating seems pretty damn thin, we chose to run it first in our K20A3 engine because it was designed by Honda for thin, low friction oils. The K20A3 has tight bearing clearances and enough oil pump capacity to tolerate the thin stuff no problem. 5W-20 is the factory fill on this engine.

For our test, we went out and bought the cheapest decent mineral based oil we could find on sale at Autozone.  We selected the factory recommended viscosity which was this 5W-20 Valvoline. Decent stuff but nothing high tech or fancy.

ZEPRO 0W-20 is just one of Idemitsu’s super mileage ultra-low friction synthetic oils in the ZEPRO line. They offer a 0W-16 formulated for Hybrids, 0W-20 dexos-1 for GM turbo engines, dexos-1 5W-30 formulated especially for the GM Ecotec engine and ZEPRO 5W-40 formulated for high-performance Euro engines like Porsche and BMW that need a thicker oil.

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