motor oil being poured into engine

061: Use a synthetic motor oil

Cost of taking action: £/$/€ LOW

A small change can make a difference

This action is another one about driving. Unfortunately, we will be transitioning from internal combustion engine cars to electric cars for many years yet, so oil and fuel economy remains a big part of our environmental challenge.

Next time you service your car (if you are really clever), or have it serviced at a garage (like me), replace the engine oil with a synthetic oil. There are several environmental benefits of doing so.

It is true that a litre of synthetic oil costs a little more than a litre of motor oil distilled from crude oil (fossil oil). In the UK, for example, the difference is around 10%. However, overall, the cost of running your car will be reduced – especially if you opt for the really good quality oils – because the synthetic will last for longer, reduce engine wear and contribute to fuel economy.

What is synthetic oil?

(With thanks to Wikipedia)

Synthetic oil is a lubricant consisting of chemical compounds that are artificially made. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials.

Synthetic oils are better performing at high temperatures than traditional oils, and also bring some environmental benefits.

Advantages of using synthetic motor oil

Advantages of using synthetic oil include:

  • better high-temperature viscosity performance (better lubrication for your engine!)
  • higher Viscosity Index and chemical and shear stability (better lubrication for your engine!)
  • less prone to thermal breakdown and oil sludge problems (less yucky)
  • extended drain intervals (change of oil needed less often)
  • less used oil waste generated (better for the environment)
  • longer engine life with protection against deposit formation in engine hot spots (your car will last longer)
  • less oil burn-off (fewer particulates emitted)
  • performance of car is improved due to less internal drag on engine (yay!)
  • improved fuel efficiency – up to 5% has been documented in fleet tests (less emissions, lower cost)


Synthetic motor oils are more expensive (per volume) than mineral oils and have potential decomposition problems in certain chemical environments. However this is mainly a problem in industrial use and should not prevent you taking this measure in a standard car.

Overall, we think this action is another one of those where collective action adds up to make a real difference, so please consider it next time your oil change is due.

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