Synthetic Oil: Scam or Real Deal?

Should you switch to synthetics?

Car mechanic repair an engine.
gilaxia / Getty Images

Look on the shelf of your local auto parts house and you'll see more oils than breakfast cereal choices at the supermarket. It wasn't so long ago that you had about a half dozen to pick from, and since they were all made from the same gunk, it didn't matter much anyway. Then in the early 1970s popped up a new batch of lubricants—synthetic oils.

The Slick Truth on Synthetic Oil

Made popular by brands like Amsoil and Mobil 1, die-hard gearheads, racers and enthusiasts started using synthetic oil exclusively. Unfortunately, it wasn't until almost two decades later that the major oil companies started offering synthetics to the masses. Despite the number of benefits over mined oil (the stuff they pump out of the ground), Americans still haven't fully embraced this advanced technology.

So what's the difference? Synthetic oil is produced in a lab, which means the only stuff in it is what they put in it. Despite the high-tech refining of crude oil, there are still contaminants in the oil that can build up and eventually damage an engine. Changing your oil and filter removes any loose particles that form, but often the build-up occurs in an isolated area of your engine, usually where it gets really, really hot. This build-up can clog oil passages and valves, which can eventually lead to reduced engine life.

There are also ecological benefits to using synthetic oil. Its viscosity (ability to lubricate) stays higher than mined oil at high temperatures, enough to even affect your gas mileage. Since it breaks down much more slowly than petroleum-based oil, you can greatly extend the time between oil changes. One truck driver drove his semi 409,000 miles on synthetic without changing the oil! Think of how much less oil would have to be collected and recycled if we used half as much every year.

So Which Do You Need?

The bottom line is synthetic oils are an easy choice. The extra bucks you spend for an oil change will be returned in no time. But ultimately it's a personal choice. There is a line of thought that high mileage cars should not be switched to a synthetic oil that late in the game. Synthetics are thought to have more detergent quality, or at least more able to loosen up old, crusty gunk inside an older engine. This can be good, but in some cases, that gunk has actually become part of what is sealing the engine. According to the theory, when the switch to synthetic is made in these old engines, gunk is cleared out and the slightly thinner and freer flowing synthetic oil begins to seep through tiny pores and cracks, creating oil leaks that weren't there prior to the big switch. Lots of technicians will tell you this is a ridiculous theory, and they may be right. But there are also lots of people who will support the theory with personal experience.