So what fluids do you need to worry about? Electric vehicles require windshield washer fluid, brake fluid, coolant, and transmission fluid.
Transmission or Gearbox fluid
Because electric vehicles do not have transmissions like internal combustion engines, the drivetrain requires less maintenance. EV transmissions have only two gears: forward and reverse. Technically, this is still a transmission, in the sense that they move the car in one direction or the other, but you do not need multiple, differently sized gears to accelerate. In fact, you’ll often see electric cars listed as “single speed” or “one speed.”
An electric vehicle is propelled by the electric motors which are capable of spinning at up to 20,000 revolutions per minute. When the electric motor spins it interacts with the transmission directly to turn the wheels and propel the car. Therefore, EV transmissions have fewer moving parts and less to lubricate and maintain. Some EV manufacturers don’t even have recommended intervals for changing the transmission fluid. For example Tesla's Model 3 owner’s manual does not list transmission fluid in the scheduled maintenance, nor does my Mercedes electric drive (which has a Tesla drivetrain). The Nissan Leaf does list gearbox fluid inspection at intervals of up to 120,000 miles - which is a lot of miles for a single owner. If you’re buying a used EV with significant mileage, this may be something you want to check.
Newer EV’s such as Hyundai and Kia recommend changing the gearbox fluid every 80,000 miles. Check the manufacturers’ recommendation for the correct type transmission fluid. Although there is not generally a special fluid for EV transmissions, each manufacturer has its own specifications and not using the specified lubricant can void the warranty, just like in any gas powered vehicle.
The battery coolant is arguably the most important fluid in an electric vehicle. The EV battery cooling system not only preserves the battery’s longevity by preventing it from hitting damaging temperatures, it also helps the car optimize battery performance in the day to day. Batteries generate electricity from chemical reactions that happen between the various battery materials. The rate of chemical reactions changes depending on the temperature. Both internal temperature, which can rise if you’re using your battery, and the surrounding ambient temperature can affect the rate of these reactions. The battery is most efficient within a temperature range of 20 to 30 degrees Celsius.
The temperature of the battery also must be regulated during charging, not just while the vehicle is running. Faster charging (and higher currents and voltages) generate more heat and the battery coolant helps offset any potential damage this can cause.
Although it would seem that the importance of the coolant would make it imperative to change frequently, this is not necessarily the case. Coolant in an EV does not interact with the air and other car parts the same way as antifreeze does in an ICE. In most systems, the coolant is isolated in metal tubes that flow over the battery modules to regulate their temperature.
Since these tubes are sealed off, the chemicals in the coolant don’t break down or become less effective over time. Maintenance schedules vary significantly between the different manufacturers. Tesla states that the coolant never needs to be changed. My Mercedes-Benz states that coolant should be checked and possibly replaced at intervals of 124,000 miles. Hyundai and Kia both show recommended maintenance times of 80,000 miles.
Again, always consult your manufacturers’ specifications if considering changing the coolant yourself. The batteries generally have long warranties over 100,000 miles, but using a different coolant than specified risks voiding the warranty.
Brake fluid in another of the important fluids in an EV. Most EV’s use what is called regenerative braking, which helps them to recycle lost energy. Because of this feature, regenerative brakes typically have a much longer lifespan than their gas powered counterparts. This does not mean, however, that you should neglect regular brake pad and fluid maintenance. Brake fluid levels should be monitored and topped off as needed. If you notice the following it may be time to change your brake fluid:
· The brakes feel ‘spongy’ or soft
· It is taking longer to come to a stop
· Your dashboard brake light turns on
At 4 years and 57,000 miles I have noticed my own brakes getting a little ‘soft’, and I’ll be having my fluid changed soon. Tesla recommends checking the fluid every two years, but most drivers report that it doesn’t need to be replaced that often. Again, check the manufacturers’ specifications if topping off or replacing on your own.
Power Steering Fluid
Automobiles have come a long way since rack and pinion steering. Most EV’s as well as ICE cars now come with an electric power steering system as opposed to the hydraulic system. The electric system is not complicated, and as a matter of fact is so simple that it eliminates the need for belts, pulleys, tubes, and fluid. Since the steering system is controlled electronically, there is no fluid to change or check and no moving parts to replace. If you’re old enough to remember having to change the power steering pump when it began to leak fluid – well, there is no more of that.
We saved the easiest one for last, since you don't technically need to check this one and you can replace it easily on your own.
If your windshield gets dirty and you push the little button to release wiper fluid and nothing comes out: don’t worry. There is no difference in the wiper fluid used for an EV. Your local auto parts store will have a perfectly acceptable washer fluid that you can pick up and replace on your own.
The more you know about electric cars, the more you should like them. Cars have been around for over 100 years and this new technology is bringing advancements fast and furious. The systems running electric vehicles are eliminating the need for moving parts, and the fluids to make them work. Gasoline, motor oil, and hydraulic fluids are becoming a thing of the past. However, even with these advancements, EV’s are still not maintenance free. Check your manual and follow the recommended maintenance schedule for changing the fluids and you’ll keep your car running smoothly and clean for a long time.