How Do I …Check my brake and transmission fluids

This week, we continue our look at how to check the different fluids in your vehicle by focusing on your vehicle’s brakes and transmission.

By Wheels

Jul 28, 2021 3 min. read

Article was updated 10 months ago

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This week, we continue our look at how to check the different fluids in your vehicle by focusing on your vehicle’s brakes and transmission.

Whenever you hit your vehicle’s brakes, brake fluid helps to amplify the braking force. Low brake fluid can coincide with a worn brake pad, which is a safety risk for driving. To check your vehicle’s brake fluid, you will need to find its canister. In most cars, this is located on the driver’s side, near the hood (the area that separates the windshield from the engine). It is typically a plastic canister connected to the brake cylinder. When you hit the brakes the brake fluid travels down the brake lines to the wheels. If your brake fluid is low, air will get into the cylinder and weakens the braking system.

You should start by cleaning the brake fluid canister before opening it. Wiping off any dirt or debris ensures that none gets into the system, which can damage it and eventually cause the brake system to fail. If the canister is plastic, the top should come off easily by turning it. If it is metallic, you will need a screwdriver to unfasten it. It is recommended that the canister stay open for no more than 15 minutes as moisture can damage the system.

Like the previous fluids we discussed, brake fluid should be filled to is at the “max” line indicator on the gauge. There are different types of fluid based on the make of the car. There is DOT (Department of Transportation) 2, DOT 3, DOT 4, DOT 5 and DOT 5.1 brake fluids. Most cars use DOT 3 or 4, but you can consult a mechanic or the car’s manufacturer to verify which type your vehicle uses. The difference between the categories is the boiling points of each. If you use the wrong type, the fluid may vaporize in the brake system, which can also damage it.

Unlike the other liquids we’ve discussed, when it comes to your transmission fluid you will typically want your car to be turned on when checking it. However, your vehicle’s owner manual may advise otherwise, so check it first and follow its direction.

First, make sure you are parked on a level surface and make sure your parking brake is engaged. The transmission oil dipstick looks similar to the one for your motor oil and is located where the transmission meets the rear of the engine. Remove the dipstick, wipe it clean and then reinsert it. When you pull the dipstick out again, you can see how much fluid in on it. There may be two “full” lines, one for warm and one for cold. The fluid should come up to the “warm” line. If not, more needs to be added. To add this fluid, remove the dipstick and then insert a funnel into the hole. Add the fluid slowly and check regularly to ensure that you don’t overpour. Once you are done, simply reinsert the dipstick.