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Defining our benchmark

There is currently no dedicated industry standard specification for hybrid engine oils. Castrol has developed a technical standard for hybrid engine oil, HYSPEC.

Introducing HYSPEC

Castrol oils are already hybrid-ready but showing how effective they are requires a benchmark. However, there is currently no specific industry standard specification for hybrid engine oils. HYSPEC is Castrol’s new technical standard for hybrid engine oils.


It isn’t a new product, ingredient or competitor comparison. It’s our own benchmark that we have chosen to measure our engine oils for hybrids against. Castrol’s HYSPEC standard enables us to show that our oils for hybrids perform against the three main challenges faced by hybrids: contaminants, engine intermittency and system inefficiencies.

We know hybrids

We have spent over 25 years researching, testing and reporting on the characteristics of hybrids. We have worked on first-generation hybrids such as the Toyota Prius, published Society of Automotive Engineers papers on hybrid operation and designed bespoke tests to replicate severe hybrid driving conditions.

Defining HYSPEC

HYSPEC at a glance

  • Over 2 billion data points collected from year-long hybrid on-road fleet trial
  • Crucial research with trusted car manufacturer partners
  • With more than two decades of hybrid vehicle knowledge; researching, analysing, and testing how hybrids operate.

What informed HYSPEC?

HYSPEC was formed from two billion pieces of data, real-world road trials, testing and insights from motorsport and vehicle manufacturers. Combining everything we know about the challenges faced by hybrids, we selected 15 hybrid relevant industry tests and supplemented them with our own bespoke tests. This enabled us to develop a credible and rigorous hybrid standard to benchmark our oils against.

The benefits of HYSPEC

For strong resistance, protected switching and fuel economy1, choose oils that perform against HYSPEC - our new hybrid performance standard. These oils demonstrate at least 25% benefit2 against Castrol’s HYSPEC standard across critical areas of contaminants, engine intermittency and system efficiency.

More about hybrid technologies and HYSPEC

1Demonstrated in industry specification and bespoke testing relevant to hybrid vehicle types. Strong resistance demonstrated by water and fuel contamination handling, protected switching demonstrated by wear, stability and cold temperature testing, and fuel economy compared to industry selected baseline oils in industry standard fuel economy tests. Fuel economy results under road conditions may vary according to vehicle type, driving conditions and style.
2Compared to minimum requirements set in industry specification and Castrol bespoke testing relevant to hybrid vehicle types, covering contaminants, engine intermittency and system efficiency.

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