Electric vehicle fluids

The automotive market is rapidly changing and interest in vehicle electrification is growing as countries enact new emissions legislation and move to ban new sales of internal combustion engine (ICE) vehicles.

Standard automatic transmission fluids (ATFs) are not optimised for electric vehicles, and further development of fluids is needed to meet the requirements of electrified vehicles drivetrains. Lubricant standards are still being developed for electric vehicles and there are many competing technologies and designs for their drivetrains.

As interest in total immersion cooling grows, there is an increasing desire for fluids that can be used across the battery, motor and transmission - requiring fluids with low electrical conductivity, low viscosity, and good thermal heat transfer properties.

How does the addition of a Croda ester affect the traction coefficient of a group III base oil?

Figure 1: Traction tests at 75°C (all fluids adjusted to 5.5 cSt).

Figure 1 shows a traction test where all fluids are at the same viscosity at standard operating temperature of 75°C. Our ester candidate neat has a viscosity of 5.5 cSt. All the other samples were made to the same 5.5cSt viscosity using a mixture of Yubase® 4 and Yubase® 6 group III base oils.

The green line represents an incorporation of 10% of the ester candidate and the orange represents incorporation of 25% of the ester candidate, respectively. Here we demonstrate a reduction in traction, even when controlling for viscosity, using our ester candidate, vs a neat group III oil.

Sustainability considerations

Alternative liquid coolant fluids, such as liquid perfluorinated compounds (PFCs) are cooling materials, but they have some significant environmental problems. For example, PFCs are relatively volatile and have a significant global warming potential depending on the exact boiling point. Further to this, they are non-biodegradable and so a source of pollution if accidentally released into the environment.

Compared to PFCs, our ester-based materials are non-toxic, non-bioaccumulative, expected to have no global warming potential and have the potential to be EU Ecolabel for lubricants compliant. A large range of our esters are on the EU Ecolabel lubricant substance classification (LuSC) list.

How can we help you formulate dielectric fluids?

We have decades of experience in the formulation of ester chemistries and we are actively developing new products for use as dielectric cooling fluids. We are leaders in friction modification and ester base oils, our experience of both allows us to help you formulate your next generation of coolants and transmission fluids.

We are developing products in two main categories:

• Very low viscosity Group V ester base oils, offering a very low coefficient of traction when formulated into Group III, IV or V base oils, suitable for formulating next-generation gearbox and e-axle lubricants.
• Unique traction reducing co-base fluids which reduce traction and wear in a Group III, IV or V-based formulation while thickening and increasing viscosity index. These fluids are suitable for replacing PAO100 and standard high viscosity esters.

We are actively researching these areas and have some exciting products in development. If you would like to work with us, to create an ester base fluid for your electric vehicle, then please contact us.