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Your expert guide to hybrid technology

At Castrol, we are experts in hybrid lubricants. We understand the unique challenges and requirements needed from hybrid engines and engine oil.

A hybrid car driving away through a tunnel, bright lights follow the car

The rise in popularity of hybrid vehicles

The drive for hybrid technology is growing. By 2025, it is expected that one in four cars sold globally will be hybrid1.


We want to keep the public up to date on the latest Castrol hybrid technologies and products to support the transition to electrification.

Discover more in our podcast

Castrol and industry experts discuss:

  • The growing demand for hybrid technology
  • Choosing the right hybrid engine oil
  • How to solve the challenges faced by hybrid engines
  • How far hybrid technology can take us and what we need to get there

The hybrid difference

Hybrid systems operate in different ways to conventional cars. This presents a unique set of challenges. Our technologists work to help ensure our oils may deliver optimum performance in hybrids. This includes partnering with leading vehicle manufacturers and motorsport teams. The right lubricant can make the difference in dealing with the challenges of hybrid engines.


How does a Hybrid work?

Hybrids are powered by multiple energy sources:

  • An internal combustion engine (ICE)
  • An electric motor
  • A battery
Hybrids repeatedly switch between the electric motor and internal combustion engine. The electric motor typically powers a hybrid at lower speeds and for urban driving. The ICE is used for higher speeds or when the battery needs recharging. In some hybrid technologies, the electric motor and ICE can work concurrently to move the vehicle. The battery can also be recharged by regenerative braking, plus external electricity sources for certain types of hybrids.


There are different types of hybrid, but the basic principle is the same for all of them. It’s just the degree of ‘hybridisation’ that varies (or how much the vehicle relies on the internal combustion engine versus the electric components).

Mild hybrid (MHEV)

Mild hybrid systems include a motor and a battery pack, which the internal combustion engine charges during normal driving. The motor provides a boost to the powertrain, but it can’t move the vehicle on its own.


Full hybrid (FHEV)

Full hybrids (also known as self-charging hybrids) have powerful electric motors. Full hybrids have a significant electric-only range, so they’re ideal for urban driving. The battery is recharged while the engine is in use. Some full hybrids also recharge the battery through regenerative braking.


Plug-in hybrids (PHEV)

Plug-in hybrids are like full hybrids, with large batteries that can be self-charging. But as the name suggests, you can also recharge plug-in hybrids using an external electricity supply. This further extends the electric-only range and improves fuel efficiency.

Discover our hybrid performance standard

Currently, there is no dedicated industry standard specification for hybrid engine oils. HYSPEC is Castrol’s new technical standard for hybrid engine oils. It’s our own benchmark that we have chosen to measure our engine oils for hybrids against.

Introducing HYSPEC

More about hybrid technologies and HYSPEC