By Gareth Fish
January 25, 2022
Although greenhouse gases have received most of the attention in recent decades, the truth is that concerns about problematic air have been around since at least the Middle Ages. Governments around the world have aggressively regulated airborne pollutants since the 1950s and have worked hard to keep the air as clean as possible for their citizens.
But as the fight against climate change has taken center stage, governments have found themselves pressed by their citizens to take even further action to reduce greenhouse gas emissions more rapidly. One of the fronts in this ongoing battle is a movement to remove internal combustion engine (ICE) vehicles from the road and replace them with more hybrid electrical vehicles (HEVs) and electrical vehicles (EVs) throughout the transportation sector, including light-duty work trucks.
Though many grease applications will remain the same during this transition, some applications are becoming more important, and others are completely new because the technology has evolved. As a result, lubricant manufacturers are starting to reconsider the way they formulate the greases that are used in EVs.
What Is in Your Truck Today
In 2020,the most recent year for which concrete data is known, there were 464,000 metric tons of automotive greases, including factory fill and service greases, sold worldwide¹. Currently, most vehicles lubricate at least 26 parts with grease, which usually serves one of four specific purposes. Greases can be used for corrosion protection or lubrication, or they’re employed to repel water and reduce the squeaking of specific parts.
There could be as many as 50 greases in a typical light-duty truck. The passenger compartment’s greases are usually used to reduce noise and offer light lubrication to specific parts. Generally, they must be plastic-compatible and are typically applied only once at the factory. Externally, greases provide antiwear protection, reduce or eliminate corrosion and resist oxidation.
Original equipment manufacturers (OEMs) apply greases to steering racks, suspension joints, joint hinges, locks and handles, brake mechanisms, shock absorbers and wheel bearings, among others. But generic greases can’t be used everywhere. Often, small volumes of specialty greases are necessary for electrical contact switches, pedal mechanisms, accessory drive bearings, seat adjusters, window winders and other applications.
How Greases Will Evolve in HEVs and EVs
Though most greases will remain the same in HEVs, it will no longer be necessary for starter-motor greases to be formulated with high shock-load resistance because the starter motors on stop-start vehicles can be permanently engaged. Another potential use of greases is for transmission electric motor bearings, though these may also be oil-lubricated depending on the OEM.
For EVs, the primary use of greases will be for the electric motor itself. To perform adequately in these situations, the greases must have long life, low noise, conduction or insulating properties and be energy efficient. These are critical because they help extend battery life in applications when range is important.
Four specific areas require energy efficiency in grease applications, including the drivetrain joints and bearings, the front-end accessory drive bearings, wheel bearings and steering mechanisms. In light-duty trucks, however, it is often challenging to achieve adequate energy efficiency because of their duty cycles.
Since most work trucks don’t reach high speeds, good lubrication films are not created, leading to energy losses. Thicker base oils can solve that problem but will increase the amount of churning losses as higher speeds are reached. While lower-viscosity oils can reduce churning losses, the lubricant films might be too thin to protect the components adequately. Therefore, a balance must be struck between the two to formulate greases effectively for electrical vehicles.
What Does This Mean for the Future?
In the short term, there will unlikely be significant changes to the greases used in light-duty trucks because most of them will remain ICE vehicles for now. As HEVs and EVs begin to penetrate the market, however, the changes to greases will significantly increase. For example, HEVs will require different starter-motor greases than their ICE counterparts, and they will also require specialty greases for their electrical motor bearings.
Although EVs are still being adapted for the light-duty truck market, new greases that are more durable, energy efficient and have long life will be necessary. Conductivity/resistivity is also an issue that will need to be addressed, but at the moment the problems are vehicle hardware-specific and can’t be generalized over the entire industry.
The challenge for lubricant manufacturers will be to develop forward-looking greases that can adapt to the unique uses in EVs and HEVs for light-duty use. It is important that they meet the needs of the moment so fleet managers and others can continue to serve their vital purpose in keeping the economy moving forward.
¹Source: “NLGI Grease Production Survey Report for the calendar years 2020, 2019, 2018 and 2017” with further analysis from Lubrizol
About the Author: Gareth Fish, PhD, is a technology manager–grease for The Lubrizol Corporation in Wickliffe, Ohio.
