How Often Should Synthetic Motor Oil be Changed?

Author: Chris Bergner  Date Posted:17 July 2019 

How Often Should Synthetic Motor Oil be Changed?

First - A Chart. (AMSOIL Product Recommendation and Drain Interval Chart)

Most motorists now understand that synthetic motor oil performs better than conventional oil. It delivers improved wear protection, offers better engine cleanliness and lasts longer. Not as well understood, though, is how often you should change synthetic motor oil.

Not long ago, it was common to change conventional oil every 3,000 miles (5000 kms) / 3 months. The practice originated in the 1960s as a way to time oil changes with the seasons. The quick lube market picked up the idea as a way to keep traffic flowing, touting it as an “insurance policy” for your engine.

Improvements in motor oil performance and engine technology have since rendered that guideline outdated. The advent of electronic oil life monitors struck a first blow. GM introduced its system in 1988, and it’s now on tens of millions of vehicles. In the USA, The state of California aggressively campaigned against changing oil every 3,000 miles, calling it wasteful. The final stake in the heart of the 3,000-mile oil change came in 2011 when American Company Jiffy Lube, the face of the quick lube industry, abandoned the practice, advising motorists to follow the guidelines in their vehicle’s owner’s manual.

If synthetic oil performs better, it should last even longer, correct?

The fact is, most oil manufacturers don’t recommend a service interval for their products. They generally advise you to follow the oil-change recommendation in your vehicle’s owner’s manual, likely due to most motorists’ unwillingness to go longer between oil changes than what’s recommended in their owner’s manual. 

Why spend more money on synthetic oil if it doesn’t last longer?

It’s a good idea for the following reasons:

Improved wear protection – Synthetic oils are more durable than conventional oils. They form a stronger protective film between metal components to shield against wear. AMSOIL Signature Series 5W-30 Synthetic Motor Oil, for example, provides 75 percent more engine protection against horsepower loss and wear than required by a leading industry standard*, extending the life of vital components like pistons and cams.

Better engine cleanliness – Synthetics’ improved resistance to heat and chemical breakdown helps guard against harmful engine deposits, so your engine remains cleaner, runs more efficiently and lasts longer. AMSOIL Signature Series scored 93 percent better for piston deposits than required to meet the latest API standard.*

Maximum extreme-temp protection – The average operating temperature of a passenger car/light truck engine has risen to 235ºF (112C), and higher under heavy loads. Synthetic motor oils do a better job of withstanding extreme heat, while their improved fluidity in cold weather helps the oil reach components faster at startup for reliable wear protection.

Most vehicle manufacturers now require synthetic oil – Automakers understand synthetic oils help their vehicles deliver improved performance, Better fuel economy and last longer. That’s why newer Toyota, GM and European vehicles, among others, use synthetic motor oil.

Not only that, but some synthetic oils, such as AMSOIL extended-drain synthetic motor oils, protect so well you can go longer between oil changes if you choose. Many motorists want to follow the guidelines in their vehicle’s owner’s manual. But lots of them still choose AMSOIL products that are capable of extending drains because they simply want maximum protection for their vehicles or the comfort of reserve protection should maintenance be delayed. Others desire the convenience of a once-a-year or twice-a-year oil change.

For these motorists, AMSOIL Signature Series Synthetic Motor Oil is guaranteed for 25,000 miles/12 months (15,000 miles/12 months in severe service). AMSOIL XL Synthetic Motor Oil is guaranteed for 10,000 miles/6 months, or longer where recommended by electronic oil life monitoring systems. They both offer an outstanding combination of performance and value.


Up To 25,000 Miles Protection

So, How will using AMSOIL affect my new car warranty? 

In the USA, practicing extended drain intervals won’t void new vehicle warranties. The Magnuson-Moss Warranty Act protects you in these situations. Plus, the AMSOIL Limited Warranty provides an extra measure of confidence. For details, visit

In Australia, using AMSOIL products will maintain you factory new car warranty. Whilst we (currently) recommend following the manufacturers drain intervals during the warranty period, SDRIVE PTY LTD (AMSOIL AUSTRALIA) is the first distributor outside of the 50 states to be able to warrant AMSOIL Signature Series and AMSOIL XL Series Extended drain intervals outside of the manufacturers warranty period. (When used in conjunction with AMSOIL EaO Filters)


For those who do not require Extended drain intervals but are looking for improved protect compared to OEM lubricants AMSOIL OE 100% Synthetic Motor Oil offers advanced engine protection, including for use with turbochargers and direct injection at an unbeatable price.


Warrant Secure logo

AMSOIL products are Warranty Secure, keeping your factory warranty intact.

They are high-performance replacements for manufacturer-branded products.

Guaranteed Performance

Like our products, AMSOIL Limited Warranty the is built with an extra measure of protection. While some other oil companies guarantee their products only until you reach a specified mileage we don't place restrictions on our warranty coverage based on total vehicle miles. The AMSOIL difference is:

We stand behind our products for as long as you use them.



*Based on independent testing of AMSOIL Signature Series 5W-30, in ASTM D7320 as required by API SN specification.

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