How to Check and Fill Fluids: Motor Oil, Coolant, Power Steering, Brake, Clutch, Transmission, Windshield

Checking automotive fluids on a regular basis is an easy way to help ensure the longevity and reliability of your vehicle.

We will go over the following:
Wanting to read the written instructions for a specific fluid? Get started by clicking a fluid type above to jump to that section of instructions.

Tools & Materials

Safety Glasses Safety Glasses

Gloves Gloves

Shop Towels Shop Towels

Funnel Funnels

Wheel Chocks Wheel Chocks

Motor Oil Oil

Coolant Coolant

Transmission Fluid Transmission Fluid

Brake Fluid Brake Fluid

Power Steering Fluid Power Steering Fluid

Washer Fluid Washer Fluid

Instructions
Most owner’s manuals will show you where these fluids are located under the hood, as well as recommending specific fluid types and service intervals. If you're not completely comfortable doing the job yourself, we'd be happy to recommend a professional technician in your area.

Get started by clicking a fluid type below to jump to that section of instructions.

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How to Check and Fill Motor Oil

location on your motor oil dipstick under the hood. usually marked orange in modern cars

Motor oil lubricates engine components and keeps everything going smoothly. It’s a good idea to check it once a month, or more often if you suspect a leak or another issue. Your vehicle’s manufacturer will specify the recommended oil weight and oil change service interval for your vehicle.

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Step 1: On a cool vehicle, check the indicators on the dipstick

Step 1: On a cool vehicle, check the indicators on the dipstick

Make sure your vehicle is turned off and sitting on level ground. Let it sit for at least thirty seconds before checking the oil level. Most vehicles have a dipstick under the hood that you’ll use to check the level of the oil. Once you find the dipstick, slide it out and wipe the excess oil off the end with a shop towel. You should see markings or other indicators on the dipstick for minimum and maximum oil levels. After wiping off the excess oil, reinsert the dipstick all the way, then pull it back out to see what the oil level is.
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Top off your oil if it reads a little low and recheck

Step 2: Top off your oil if it reads a little low and recheck

The oil should be reading close to the maximum marking. If it’s a little low, add oil carefully to top it off. A funnel is helpful when you’re doing this. Make sure you’re adding where the oil fill cap is removed, not the dipstick tube. Add a few ounces at a time, and re-check it to make sure you don’t overfill it.

Do It Right: If your level is at or below the minimum mark, it’s important to add oil immediately. This could be an indication that your vehicle is leaking or burning oil—you should seek the help of a professional to prevent further damage.

If it has been 6 months or 5,000 miles, you know your oil needs replaced and you would like to do it yourself, check out our video on How to Change Oil & Filter.
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Check the color of your oil. Oil that is Amber should be good for 3k-5k miles.

Step 3: Check for color and other warning signs

Your motor oil should be slick and smooth, in a yellow or amber color. Grittiness or particles in the oil can indicate that components are wearing down, which is a major issue. If you notice a milky color, check to see if there’s any condensation on the inside of the cap. If there is, it could be an indication of moisture that hasn’t been burned off. But it could also mean that coolant is leaking into the engine oil, which is a more serious situation. Other indications of this can be brownish coloration in the coolant reservoir or white smoke from the exhaust. If any of those symptoms are present, you should have your vehicle towed to a shop to avoid damage to your engine.

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How to Check and Fill Coolant

location of your antifreeze reservoir under the hood

It’s recommended you check your coolant level with each oil change.


Do It Right: Always wait for your engine to cool completely before checking coolant. Two to three hours is safe if you’ve been driving. Even though some reservoirs will give an accurate reading whether the coolant is hot or cold, pressurized coolant can spray and cause burns.

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min/max marking should be on the side of your tank

Step 1: Check your reservoir tank min/max markings

To check the level, you’ll usually see a tank that has minimum and maximum marks on it. Also, take off the radiator cap to make sure it’s filled to the top. Usually when just topping off your coolant, you can add it directly into the reservoir tank. Only add coolant that’s specifically approved by your vehicle’s manufacturer. And if you suspect a leak, have your vehicle diagnosed by a professional as soon as possible.

If it is time to flush and fill your antifreeze and you would like to do it yourself, check out our video on How to Flush & Fill Antifreeze.
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How to Check and Fill Power Steering Fluid

Power Steering Reservoir upper and lower level markings

It’s a good idea to check your power steering fluid at every oil change, and change it as often as specified by your vehicle’s manufacturer. Similar to other fluids, you’ll usually find a reservoir or dipstick in the engine bay. Check the reservoir or remove the dipstick to check the reading… and top it off if necessary. To avoid causing damage, only use the type of power steering fluid specified by your vehicle’s manufacturer.

Pro Tip: If this fluid is something you’re having to add regularly, you probably have a leak. Have the problem looked at by a professional technician to avoid steering problems and safety issues.

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How to Check and Fill Brake Fluid

Brake Fluid tank and the Max line markings

Outside of any brake issues, it’s beneficial to check your brake fluid level at every oil change.

Step 1: Check the markings on the brake fluid reservoir
Most vehicles have a brake fluid reservoir under the hood, sometimes under a plastic cover near the bottom of the windshield. Just make sure the level falls between the marks for minimum and maximum.


Do It Right: If you can’t see through the fluid—if it’s dark or cloudy—it needs to be replaced. If you’re adding to the reservoir, be sure only to use the brake fluid specified by your vehicle’s manufacturer.

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How to Check and Fill Clutch Fluid

Example Location of your clutch fluid reservoir

If your vehicle has a manual transmission with a hydraulic clutch, you’ll want to check your clutch fluid level at each oil change. Your clutch fluid reservoir is typically located near the brake master cylinder toward the back of the engine bay. Specific location should be in your owner’s manual.
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Opening the lid and checking where the clutch fluid lies in the max/min markings

Step 1: Check fluid level by checking the markings on the reservoir

The fluid level should fall between the markings for minimum and maximum levels. Some older vehicles may have metal reservoirs that require you to remove the cap to see the level. Hydraulic clutches use the same type of fluid as hydraulic brake systems, so if you do need to add fluid, only add fluid that meets the DOT specification recommended by your vehicle’s manufacturer.
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How to Check and Fill Transmission Fluid

example location of a transmission fluid dipstick under the hood

Transmission fluid serves to cool and lubricate components like gears, clutches and valves inside your transmission. Some vehicles come with transmission fluid that isn’t intended to be changed. Other vehicles will recommend changing the fluid every thirty thousand to a hundred thousand miles. But if you’re having any transmission issues—like rough shifting or surging—start by checking the fluid. In some cases, you’ll find a dipstick—others will require a professional technician.
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With engine on, place in park, cycle through the gears and check the dipstick

Step 1: With engine on, place in park, cycle through the gears and check the dipstick

Always follow the procedure specified by your vehicle’s manufacturer for checking transmission fluid. If your vehicle has a dipstick, the process will be similar to how you’ve checked other fluids. But there are a few differences. When you check the transmission fluid level, you’ll want to have your engine turned on and transmission in Park or Neutral, depending on the vehicle. Setting your emergency brake and chocking your wheels is a good idea for this procedure. But before checking the dipstick, put your foot on the brake and use your gear selector to cycle through all the gears with the vehicle idling. This will allow a more accurate reading.

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Transmission dipstick markings

Step 2: Check the color and add more as needed

The fluid should feel smooth, and be amber or red in color. Fluid that’s dark, cloudy or gritty indicates a problem that requires professional attention. If you need to add transmission fluid, pour a small amount into the fill tube. In most cases, topping off this fluid won’t require more than a pint, so add a small amount at a time. A funnel will make this easier.

Do It Right: It’s very important not to spill any outside the tube—transmission fluid can ignite if it makes contact with a hot manifold.

Make sure only to use the transmission fluid type specified by your vehicle’s manufacturer.
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Recheck after cycling through the gears again

Step 3: Recheck after cycling through the gears again

Put your foot on the brake and cycle through all the gears again. Recheck the dipstick to make sure the fluid is at the right level. Make sure when you’re done to replace the dipstick securely—some will latch or lock into place.
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How to Check and Fill Windshield Washer Fluid

filling up windshield washer fluid tank

Even though it isn’t necessary to your vehicle’s performance, windshield wiper fluid is an important part of driving safely… and it’s probably the easiest fluid to maintain. There are several varieties to choose from: freeze protection for cold weather, bug-wash for summer or all-season for year-round visibility. The reservoir should be easy to find, and all you have to do is pour fluid in until it’s full. Most vehicles will only have one reservoir, even if there’s a rear wiper, but in some cases you’ll find a washer fluid reservoir in the rear also.
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The automotive repair work depicted in this series is performed under the direction of the manufacturer of the product featured. Prior to undertaking any of the demonstrated repairs on your vehicle, we suggest you consult with a certified mechanic or another professional who can adequately advise you of the proper repair or remedy required. O’Reilly Automotive Stores, Inc. and its affiliates (“O’Reilly”) disclaims any responsibility for injury or damage resulting from a viewer’s attempt to recreate the repairs shown in this series.