Blog / Synthetic vs mineral oil

Engine Care · 4 min read

Synthetic vs Mineral Oil: Which Does Your Car Need?

The choice between synthetic, semi-synthetic, and mineral oil isn't really a preference decision, it's determined by what your specific engine was designed for, and using the wrong one isn't simply a minor inefficiency.

What the three types actually are

Mineral oil is refined directly from crude oil with minimal processing. Semi-synthetic blends mineral oil with synthetic base stocks. Fully synthetic is chemically engineered to a consistent molecular structure rather than refined from crude. Broadly, synthetic performs better across temperature extremes, breaks down more slowly, and lasts longer between changes, which is why it costs more.

Why this isn't just a budget choice

Modern engines, particularly turbocharged ones, are frequently designed and specified for fully synthetic oil from new, since it copes better with the higher temperatures and tighter tolerances involved. Using a cheaper mineral oil in an engine specified for synthetic isn't simply a lesser version of the same thing, it can genuinely fail to protect the engine adequately under real operating conditions.

How to know what your car actually needs

The handbook specifies the exact oil grade and type required, and it's worth following that precisely rather than assuming any oil of the roughly right viscosity is interchangeable. If you don't have the handbook, the requirement is also usually printed on or near the oil filler cap, or available from the manufacturer directly using the registration number.

Older cars and mineral oil

Some older, simpler engines were designed around mineral oil and don't specifically need synthetic, though switching to synthetic in an older engine rarely causes problems. The bigger risk runs the other way: using a cheaper oil in an engine that genuinely requires synthetic.