How Long Does Synthetic Oil Last?

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Change Synthetic Oil

Most vehicle manufacturers today will specify the use of Synthetic engine and gearbox oils, or at very least, a synthetic blend oil. Synthetic oils can extend engine life and performance, outlasting traditional mineral based products and so owners tend to extend the gap between oil changes. But how often should you change a synthetic oil?

First, we’ll consider the benefits of Synthetic based oils.

Benefits of Synthetic Oil

Oils If you aren’t already using synthetic oil in your vehicle, you should definitely consider it! There are numerous benefits, especially for diesel engines. Just some of those advantages include:

  • More consistent viscosity at temperature extremes
  • Increased resistance to chemical breakdown and oil sludge problems
  • Increased service life, resulting in environmental benefits due to less waste oil produced
  • Protection against ash build up in oil, reducing wear on engine components
  • Potential fuel economy gains, up to 5% in some configurations
  • Possible engine life increase

It is for this reason that Synthetic oils have become so common place, not only in the automotive industry but also in the aviation sector.

Why does Synthetic Oil need changing?

Reading through the above list of benefits, you’d be forgiven for wondering why oil needs changing? Mechanics will regularly hear “There were no low-oil-level lights on the dashboard, so I kept driving” or “I just topped up the engine with any old oil I could find”.


Replacing engine oils is crucial for the long-term health of your engine. Through use, engine oil collects small particles of metal from component wear as well as picking up combustion by-products.

Additionally, over time, lubrication and performance enhancing additives begin to break down. Consequently, as engine oil ages, it becomes less effective.

Therefore it is critical to replace engine oil on a periodic basis. But how often?

Change Synthetic Oil
Change Synthetic Oil. Source:

Synthetic Oil Change Interval

Oil service intervals depend on the usage of the vehicle and the manufacturers specifications. If high loads are placed upon the engine and the vehicle is used in a harsh environment, such as off-road, you should change your oil more frequently.

For daily use, 5000 – 7500 mile oil changes will be sufficient. If you do not cover those distances in a year, then change it bi-annually. If however, you typically drive short-distances, averaging below 60mph, you must change your oil every 1,500 miles. The reason is the engine and engine oil never reach optimum operating conditions and cause the oil to degrade rapidly!

If you are still in doubt, reference your car’s owner’s manual. The manufacturer will list the necessary services, usually, after a number of miles or a period of time has elapsed. They may also print the harsh-environment servicing frequencies.

A trusted garage will also be able advise on the frequency of oil changes.

How Often To Change Oil Filter With Synthetic Oil?

Engines are fitted with at least one oil filter, it’s purpose is to sift fine metal and carbon particles from the oil and prevent them from compounding wear.

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Over time, just like engine oil, these too will operate less effectively and so it is vital to replace these at the same time as a full engine oil drain. When refitting, fill the filter with fresh engine oil so upon the first start-up, internal components are lubricated right away.

Check Levels

In between engine oil changes, regularly check the oil level. This can be done using the provided engine oil dipstick.

Checking the oil is simple.

  • Park on level ground.
  • Locate and lift out your dipstick.
  • Wipe it with a clean cloth.
  • Then, fully reinsert the dipstick, before removing it a second time. This shows your oil level.

Your oil level will ideally sit halfway between full and empty. If it reads below empty, add small increments of oil till the level is correct. If you find your oil level drops rapidly, you may need to consult a mechanic as the engine is burning oil as part of the combustion process.

The oil on the stick should be examined too. If your oil is black and has a strong smoky smell, it wouldn’t hurt to replace the engine oil. If it is murky in appearance and brown in colour, resembling mud, you should replace the oil immediately!

Final Thoughts

Regular servicing of a vehicle will increase it’s performance and life, reducing additional costs that arise from lack of maintenance. They may also help you sell your vehicle, as a full service history and supporting documentation is desirable to potential buyers.

Additionally, having a garage service your vehicle on a regular basis will allow the garage to inspect other components and parts for damage or wear, making your car safer and more reliable.


Do not neglect your engine oil, replace it often, use synthetic oils and your engine will thank you with years of trouble free motoring.

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