If your car's owner's manual says it does, you do.
For many consumers, whether to spend extra money for synthetic oil for an oil change is a difficult question to answer.
Manufacturers of synthetic oil promise more miles and better performance when compared with conventional motor oil, but it comes at a higher cost — sometimes twice as much per oil change. Is it worth the extra money?
Typically, high-performance vehicles will be more likely to require synthetic oil, as will vehicles that have a turbocharged or supercharged engine. However, if your vehicle does not require synthetic oil, the choice is trickier - and there is no clear answer.
Synthetic oil generally resists breaking down for longer than conventional motor oil (typically 7,500 miles to 10,000 miles, sometimes up to 15,000 miles, as opposed to 3,000 miles to 7,500 miles for conventional oil). That makes the extra cost a wash, if you have half the number of oil changes, but each one costs you twice as much. Other touted benefits include cleaner engines, better flow in cold temperatures, better protection when it's hot outside and better performance with turbocharged engines.
There are also synthetic blends. As the name implies, these are blends of synthetic and conventional oils. They straddle a middle ground — they cost more than conventional oils but less than full synthetics, and are said to last longer than conventional oils but not quite as long as synthetics — but again, that's a hard number to pin down since manufacturers are vague with their claims. An independent testing lab we spoke with said that synthetics often didn't perform much better than conventional oils do.
Still, older engines may benefit from synthetics because it is less likely to form sludge.
If your car doesn't require synthetic oil you should perform a cost/benefit analysis, but that can be difficult to do due to vague claims made by manufacturers. There may be no reason to spend more on synthetic oil, except for peace of mind.