Synthetic oil

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Synthetic oil is a lubricant made by chemically modifying or building molecules, rather than just refining crude oil. While many synthetics start from refined crude oil, some can be created from other materials. The exact formulas and additives are often trade secrets.

Types of synthetic oils
- PAO (poly-alpha-olefin) base stock (API Group IV): a fully synthetic, widely used base.
- Esters (Group V): another fully synthetic option, known for good lubricity.
- Group III base oils: highly refined mineral oils that some brands market as synthetic.
- Semi-synthetic (synthetic blends): mixes of mineral oil and synthetic oil to balance cost and performance.

How they’re made
- Most synthetic base stocks are engineered to have a controlled molecular structure and consistent properties.
- The base stock plus additives is tailored for specific performance goals.

Benefits
- Better performance in very cold and very hot temperatures.
- Higher viscosity index, so oil thickness stays more stable.
- Strong chemical and shear stability; resists oxidation and sludge.
- Less oil evaporation; often longer service intervals.
- Helps reduce engine wear and deposit formation, especially in hot spots like turbochargers.
- Can improve engine efficiency in some cases.

Drawbacks
- Significantly more expensive per volume than conventional mineral oils.
- Some formulations may have compatibility or stability considerations in certain environments.

Note
- “Full synthetic” is commonly used as a marketing term and isn’t a fixed technical standard.