How Long Does Full Synthetic Oil Last?

The synthetic oil in your car engine has an incredibly challenging job. From lying cold in the bottom of the engine oil pan, you need to jump up to the valve gear at the very top, then flow back down, and this has to happen almost instantly when you start the engine. The oil protects everything inside your engine: bearings, pistons, cylinder walls, and all the other parts that move or touch something that does.

After the initial cold startup, the oil must continue to protect no matter how hot it gets and how hard the engine is running. This has to be done for a period of months, if not years, through numerous short trips, long cruises, and (for some) occasional racetracks or twisted two-lane flogs. You depend on your car’s oil to do its job flawlessly through the bitter cold of the northern winters and the sticky warmth of the southern summers — all while fighting rust, contaminants, and lock-ups.

Change Interval for Synthetic Oil

There’s a lot of nonsense about when to change your synthetic oil. If your vehicle runs synthetics — and most of them do these days — the best place to find the correct oil-change interval is the owner’s manual. The recommended manufacturer’s synthetic-oil change intervals vary greatly. For vehicles in the long-term test fleet of Car and Driver, these intervals range from 6000 to 16,000 miles (and almost always include changes to the oil filter).

Most modern vehicles have change intervals in the 7500-to-10,000-mile range — usually a good schedule to use if you absolutely can’t find any information about the oil change interval for your vehicle. Manufacturers also have a special set of recommended synthetic oil-change intervals for vehicles driven under severe conditions such as Mojave Desert heat or Alaskan cold — or for vehicles that spend most of their time on dusty roads. Many newer vehicles have oil quality monitoring systems that keep track of driving conditions — long journeys, engine temperatures, and other engine parameters. The algorithms in these systems calculate when you need to change your oil and alert you when it’s time.

If your vehicle is older, you might want to consider one of the synthetics billed as “high mileage” oil. These oils do have a different combination of additives that might be a little better suited to engines with a lot of wear, tear, and miles on them. There is no hard-and-fast rule, however, that you should put them in your car’s crankcase. The most important thing is to use a synthetic with the same SAE viscosity (named for the engineering organization SAE International) that the factory used to fill your car in the first place and to follow the correct oil-change interval. This will help your car to run properly and your engine to last longer.

So How Long Does Synthetic Oil Last?

Synthetic oil is the most expensive of all types of lubricants used to run the engine. It has a longer lifespan and provides protection from heat, erosion and sludge. There is also a synthetic blend that delivers better performance than conventional oil and costs less than pure synthetic oil. The additives and detergents in it ensure a longer life. It wears out at a slow rate because its chemical base makes it thick at low temperatures and thin at high temperatures. Depending on the brand, synthetic oil can last between 5,000 and 15,000 miles. Some companies like Mobil 1 and Royal Purple are offering better products than other brands.

Factors That Shorten The Life Of Engine Oil

There are several factors that can cut that lifespan short. Synthetic oil may not perform to your expectation for these following factors:

  • The engine in older vehicles. Engines in newer cars are more compatible with synthetic oil.
  • Performance vehicles. Performance-based engines require more oil changes they burn the fuel at a faster rate.
  • Driving style. Rough driving and aggressive acceleration shorten the life of engine oil.
  • Hauling heavy stuff. The engine works harder when you are towing cargo around.
  • Extreme climate conditions. Extreme cold and heat puts more strain on the oil.

Does synthetic oil make a difference?

Today’s engine oils have evolved into brilliantly engineered blends of refined petroleum and sophisticated additives that allow them to retain their protective properties over all those months and miles and inhospitable conditions. Some are suitable for light use over a reasonable period of time, while others are better suited for longer and harder use. Today’s highest-performing, longest-lasting engine oils are synthetic, which means that they are typically engineered and manufactured from chemically modified petroleum components (and some other materials).

Synthetics can provide better start-up performance and flow at temperatures down to-40 Fahrenheit, then withstand extremely high temperatures without oxidizing, thickening or turning black. With automakers increasingly using thinner, ultra-low-viscosity (thickness) oils to reduce running friction to improve fuel efficiency, synthetics can be formulated to much lower viscosities while retaining their protective and lubricating properties. They are typically two to three times more expensive than regular oils, but they are cleaner and more robust, have superior chemical and mechanical properties , especially in extreme temperature ranges, and can retain these properties longer between changes.

By Jon ‘ShakataGaNai’ Davis, CC BY 3.0,

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