The pressures and temperatures inside an engine are intense. Even during normal operation, the heat of combustion and the rush of the exhaust gases is enough to eventually grind down the sturdiest of metals. Combined with the friction created during cold starts when oil is mostly sitting at the bottom of the oil pan, the wear suffered by an engine over the course of its lifetime can affect both performance and efficiency as the years go by.
In searching for ways to improve gas mileage, people rarely stop to think about the impact that engine wear can have on their fuel economy. An engine which has not been properly maintained has a far greater chance of using more fuel than it needs to when compared to a motor that saw regular servicing. A necessary part of any automotive maintenance program is of course regular oil changes, but the choice of oil that you decide to pour into your engine can have a significant impact on wear, and by extension, fuel economy.
Some mechanics will recommend using petroleum-based oils in combination with a regular change interval of around 3000 miles as the best way to reduce engine wear. Unfortunately, this is simply not enough, especially if you live in a climate that sees extreme cold or heat. In order to best protect your engine, you should use a synthetic lubricant. For example, when starting a vehicle in low temperatures, it takes standard oil several seconds to completely create a protective coating over your internal components, due to the fact that the cold causes it to lose viscosity. Over time, this creates significant wear in a motor, because for that brief period of time the engine suffers from internal friction. Synthetic oil is not nearly as affect by temperature when it comes to viscosity. This also makes it ideal for hot environments, where synthetics avoid the breakdown and lack of coverage that petroleum oils often experience. The engineering involved in creating synthetic oil ensures that it is never too thick or too thin for the application you are using it for.
There are a number of ways to improve gas mileage, but using a synthetic oil has an additional bonus on top of helping you save money at the gas pump. By preventing wear in your engine, you are also helping to make sure that your car will keep on running like clockwork for hundreds of thousands of miles.