What’s the Deal With Synthetic Oil?

We’re often asked if it’s worth switching to synthetic oil.  Sometimes the answer is simple.  If the vehicle’s manufacturer requires it, anything other than synthetic motor oil voids the warranty.  Otherwise the trade-offs with conventional motor oil can be a bit complicated, involving more than just cost.  There’s even some controversy concerning whether its right oil for older cars.

Just What is Synthetic Oil?

All engine oils actually start with refined crude.  So what makes synthetic different from conventional motor oil?  It’s chemically modified by additional distillation, broken into smaller molecules, and receives superior additives.  All that makes it a motor oil tailored to the needs of modern engines.  And twice as expensive, or more.

But you need to read the “fine print” to know exactly what you’re getting.  Blended or semi-synthetic products combine conventional oil with synthetic to reduce costs, with some reduction in the benefits.  Many people recommend it.  “Synthetic” may contain some un-modified compounds, and “100% synthetic” is (no surprise) 100% the real deal.

The Benefits of Synthetic Oil

The bottom line is improved engine performance and lifetime.  Here are the key specific benefits of synthetic oils.

  • Flows better at cold temperatures.  Since its lubrication reaches engine parts sooner, there’s less wear and the engine should last a bit longer.
  • Better wear protection at high temperatures.  That’s especially important for desert driving, and especially important for vehicles with turbo chargers.
  • Provides longer-lasting protection.  It’s more resistant to oxidation and thermal breakdown so it needs to be changed less often.  That often means 2 to 3 times the interval between oil changes.  But never exceed the auto manufacturer’s recommended schedule.
  • Improved performance.  Better viscosity at temperature extremes, improved lubrication, and a cleaner engine can mean more torque and horsepower, better fuel economy, and less wear on engine parts.

Considering Switching to Synthetic Oil?

Consumer Reports suggests sticking to conventional oil for most vehicles to reduce costs, but notes a few important exceptions (https://www.consumerreports.org/cro/news/2015/07/when-should-you-consider-synthetic-oil/index.htm).

  • You make lots of short drives.  If so, conventional oil doesn’t get warm enough to burn off impurities and evaporate moisture. Either change your oil more often or use a synthetic or blend.
  • You do a lot of driving in very hot summers, or very cold winters.
  • You do heavy hauling or towing.

The cost of the oil itself is only part of the cost of an oil change, so the total price difference isn’t so great.  If you can go twice the mileage between changes it just might be a net savings.

A Little Controversy

Some mechanics say that synthetic shouldn’t be used during engine break-in or in high mileage vehicles.  Others say that you shouldn’t switch back to regular.  That’s a bit strange considering the existence of blended products.

Synthetic oil in older cars does do a better job of cleaning out deposits of sludge buildup.  And there’s products specifically for older cars, such as Castrol EDGE High Mileage.  Just make sure you and your mechanic fully understand the manufacturer’s requirements, the condition of your vehicle, and the specific product used.