John Baker | May 16, 2016 2:04 PM Although gas is hovering around only $2.00 per gallon these days, increasing fuel economy is still a top priority for most automakers, due in large part to more strict corporate average fuel economy (CAFE) requirements on the horizon. One strategy automakers are using is widespread use of synthetic lubricants. How do synthetics increase fuel economy compared to conventional lubricants? Reducing viscosity increases fuel economy At one time, most passenger cars/light trucks used 10W-40 motor oil. Then it was 5W-30. Today, many vehicles call for 5W-20 and 0W-20 oils. And an even lower viscosity, 0W-16, is on the horizon for certain newer vehicles. The lower the oil’s viscosity – defined as its resistance to flow – the more readily it will flow. Imagine a jar of honey and a glass of water. Stirring water with a spoon requires less energy than stirring honey. The same principle applies to your engine and motor oil.