How Often To Change Synthetic Oil

Updated: May 17, 2024

Synthetic oils contain chemically modified compounds and high-quality base oils. That means synthetics can go longer between oil changes.

Motor oil is an engine’s lifeblood. It cleans, lubricates, cools, cushions and protects engines and other mechanical parts. Motor oil also holds in suspension sludge, harsh chemicals, contaminates and abrasive particles — things that cause engine wear.

Synthetic oil is used in most modern vehicles, especially high-performance and turbo-charged. Here’s what most of us need to know.

What Is Synthetic Oil?

Virtually all full-synthetic oil comes from high-quality crude (base) oil. Enhanced refining methods and chemically enhanced friction modifiers produce a product with exceptional engine protection not found in conventional or synthetic blended oils.

There is no standard for synthetic oil, making “full-synthetic” a marketing term. This also means no two brands are exactly the same.

Automotive manufacturers choose synthetic oil for its low viscosity. Low viscosity oil permits an engine to spin easier, run cooler and dissolve deposits left by contaminated and oxidized conventional oils. This increases gas mileage, lowers engine tailpipe emissions and keeps the engine cleaner, extending its life.

Full-synthetic oils are not recommended for pre-1990 vehicles, or those that specifically require conventional motor oils. Conversely, those same exceptional qualities that make full-synthetic so beneficial can worsen already failing oil seals and gaskets in neglected engines. Using full-synthetic in a well-maintained engine rarely causes problems.

The Difference Between Synthetic Oil and Conventional Oil

Both synthetic and conventional oil starts out as crude oil. However, not all crude oil is the same.

According to the U.S. Energy Information Administration, crude oil is classified by density and sulfur content. Higher-quality crude goes through extensive distilling processes to produce synthetic oil. Adding state-of-the-art artificial additives (antioxidants, corrosion and foam inhibitors, anti-wear agents, detergents and water dispersants) produces oil that offers far superior engine protection than conventional motor oil.

Although more affordable than synthetics, conventional oil breaks down faster under extreme loads.

How Long Does Synthetic Oil Last?

It depends.

Various factors affect how long before any oil breaks down. Whether inside your engine or in a bottle on a shelf, over time oil degrades and no longer protects parts from wear and tear. Once in the engine, motor oil should be changed at least once a year, regardless of mileage.

The shelf-life of a sealed bottle of oil can be two to five years, depending on the producer. This depends on temperature and how the oil is stored.

Unless you are 100% positive no dust, debris, or moisture made it into an opened bottle of oil, don’t use it.  Even if it’s an expensive bottle of synthetic oil, the cost will pale in comparison to the engine repair cost if you top it off with contaminated motor oil. Always recycle oil or hazardous waste responsibly.

Do Synthetic Oil Containers Have Expiration Dates?

Again, it depends. While some producers do add a “Best By” or expiration date, most add the production date to the bottle. John Paul from Pennzoil technical support says a JAN2323 production date on their bottles refers to January 23, 2023.

How Often To Change Synthetic Oil

Yep, it depends.

Under “normal” driving conditions, synthetic oil can go 10,000 to 15,000 miles, or six to 12 months, between changes. Follow these guidelines for changing oil under these extreme driving conditions:

Short trips

If you’re commuting less than 10 miles a day, oil cannot get warm enough to burn off moisture and impurities. Change oil every 5,000 miles or every six months, or sooner.


Living in an area with extreme temperature fluctuations (0 degrees in the winter to 100 degrees in the summer) reduces motor oil’s ability to protect your engine. Change oil right before and right after winter and summer, and after no more than 5,000 miles.

Harsh driving conditions

  • High-speed highway driving: Change oil every 6,000 miles or six months.
  • Driving on dusty, gravel, sandy or salty roads: Change oil every 3,000 miles, and check the air filter as well.
  • Driving at low speeds for long distances: Change oil every 3,000 miles, or three months.
  • Stop-and-go driving or idling for long periods: Change oil every 4,000 miles, or four months.
  • Towing a trailer: Change oil every 4,000 miles, or four months — more frequently in sandy, or muddy conditions.

When in doubt, always follow the manufacturer’s recommended service intervals or sooner. And definitely change when the oil life monitor reaches 25%.

Synthetic Oil Change Cost

The high cost of quality base oil, expensive refining processes and pricey additives make synthetic oil more expensive than conventional oil.

According to Kelley Blue Book, expect to pay between $65 and $125 for a full-synthetic oil change, compared to $35 to $75 for a conventional oil change. This includes replacing the oil filter. Many repair shops offer discounts on oil changes. Look for promotions and coupons.

DIY Oil Change

Most shops don’t charge a whole lot more to change your oil and filter than you’d pay for the supplies. So why DIY? If you have the tools, DIY oil changes save time and may save you some money. That, plus the satisfaction of changing oil yourself, are excellent motives.