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Semi Synthetic and Fully Synthetic Oil

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Making sure your vehicle has the correct oil will improve performance and protect your vehicle from preventable damage. Read more for an explanation of the differences between semi and fully-synthetic oil.

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When you have your engine oil changed as part of your regular car service or FuelService Plus you want to be sure that the replacement oil offers the best protection and performance for your vehicle, that it is recommended by your vehicle's manufacturer and that it will help improve your fuel economy.

Oil is one of the most important 'parts' of an engine. It reduces friction and wear, helps manage engine heat and protects against the effects of high temperatures and damaging contaminants.

Using incorrect or low quality oil will reduce the lifespan of key engine components.

Semi synthetic oil or fully synthetic oil?

Synthetic oils are specifically manufactured to provide consistent, superior performance. Their main advantage over mineral oils is that they provide protection to the engine across a far wider range of temperatures - up to an engine's maximum temperature and beyond. They do not have the impurities found in mineral oils or degrade as quickly, and they are thinner, helping to improve fuel efficiency.

Semi synthetic oil

Semi synthetic oils are cheaper than fully synthetic as they are a mixture of synthetic and mineral oil. Engines requiring semi synthetic oil must use at least semi synthetic oil (not mineral oil) but may benefit from upgrading to fully synthetic oil for increased protection and performance.

Fully synthetic oil

As the name suggests, fully synthetic oils are purely synthetic with no mineral oil. They offer the highest levels of performance and are an essential requirement for many modern engines (check your handbook if you're unsure of the requirement for your car).

Booking at Halfords Autocentres

Booking a Service?

Whether your car requires fully synthetic oil or if you'd just like to benefit from the increased performance gained by upgrading from semi to fully synthetic, select the 'Oil Upgrade' product when you book your Service online for just £22.

Booking a FuelService Plus?

Our FuelService Plus includes a full oil change, so if you're booking this service be sure to select the option with the right oil for your car.


Interim Service

from £85.00


Full Service

from £155.00


Major Service

from £219.00


Interim Service and MOT

from £105.00

Saving £34.85


Full Service and MOT

from £170.00

Saving £39.85


Major Service and MOT

from £229.00

Saving £44.85