Synthetic vs Mineral Engine Oil — What’s the Difference?

The Three Types

Type Description Price Range (5L) Change Interval
Full Synthetic Chemically engineered for maximum performance £25–45 10,000–20,000 miles
Semi-Synthetic Blend of synthetic and mineral base oils £18–30 7,500–10,000 miles
Mineral Refined from crude petroleum £12–20 3,000–5,000 miles

Which Should I Use?

Most modern cars (2010+) require fully synthetic oil. Your manufacturer specification code (e.g., VW 508 00, Ford WSS-M2C913-D) almost always mandates synthetic. Semi-synthetic is suitable for some older vehicles, while mineral oil is now only appropriate for classic cars.

Bottom line: Check your handbook or use our oil finder. If it specifies a modern spec code, you need fully synthetic.

Frequently Asked Questions

Can I switch from mineral to synthetic?

Yes — switching to synthetic won’t damage your engine and will provide better protection. However, in very high-mileage engines, the improved cleaning properties of synthetic oil can loosen built-up deposits, potentially revealing existing gasket leaks.

Is fully synthetic oil worth the extra cost?

For any car that requires it, absolutely. The longer change intervals alone often offset the higher price. For older cars that don’t require it, it’s still beneficial but not essential.

Can I mix synthetic and mineral oil?

In an emergency, yes — they’re compatible. However, mixing reduces the performance advantages of synthetic oil. Top up with the same type when possible.

Recommended Products

Castrol EDGE 5W-30

Castrol EDGE 5W-30

Premium fully synthetic engine oil

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Mobil 1 ESP 5W-30

Mobil 1 ESP 5W-30

Advanced full synthetic motor oil

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Oil Drain Pan & Funnel Kit

Oil Drain Pan & Funnel Kit

Essential kit for DIY oil changes

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