How to Check Your Car Fluids at Home

Park on level ground, open the hood, and compare each fluid against its marks: read the oil on the dipstick, and read coolant, brake fluid and washer fluid on the side of their reservoirs. Your owner’s manual shows where each one is, which fluid your car takes, and how often to check.

That last part isn’t a formality. Fluid types and intervals vary by vehicle, and the wrong fluid can do real damage, so this guide tells you how to look and what a reading means. Your manual tells you the specifics for your car.

Time: A short job once you know where everything is.

Difficulty: Easy.

What you need

• Your owner’s manual
• A clean rag or paper towels (good towel options)
• A flashlight
• Gloves
• A funnel, only if you’re topping up

Before you open the hood

Park on level ground and set the parking brake. Most checks are safest on a cool engine, and coolant has to be checked cold.

Stay away from the cooling fan. Kia’s manual warns that it can run even when the engine is off, so keep your hands, tools and loose clothing clear.

If you have a hybrid or EV, leave orange cables alone. Orange marks high-voltage wiring, and it isn’t for anyone without the right training and equipment. Your manual shows which items are yours to check.

The checks at a glance

Fluid	How you check it	If it’s low
Engine oil	Dipstick, following your manual	Add the oil your manual specifies, a little at a time
Coolant	Reservoir marks, with the engine cool	Top up per your manual, and look for a leak if it keeps happening
Brake fluid	Reservoir MIN and MAX marks	Get it inspected. Don’t just top it up
Washer fluid	Reservoir, or a low-level warning on some cars	Refill any time
Power steering fluid	Reservoir, if your car has one	Follow your manual, and check for leaks
Transmission fluid	Depends on the car. Many have no dipstick	Leave it to a shop

How to check each fluid

1. Check the coolant first, while the engine is cold. Look at the translucent reservoir, not the radiator. The level should sit between the MIN and MAX marks, or the F and L marks on some cars.

   Never open a hot cooling system. Kia’s manual warns that hot coolant and steam can blow out under pressure, even with the engine off, and cause serious injury. Don’t remove the radiator cap or reservoir cap until the engine is fully cool.

2. Check the brake fluid. Your manual shows where the reservoir is. The level should sit between the MIN and MAX marks on its side.

3. Check the washer fluid. This is the one fluid you can top up without much thought. NHTSA suggests filling the reservoir with winter de-icer fluid before cold weather, since it runs out fast in a storm.

4. Check the power steering fluid, if your car has a reservoir. Your manual will say whether there’s one to check and how to read it.

5. Check the engine oil the way your manual says. Many manuals want the engine warmed up first, then shut off for a set time so the oil can drain back down. Mazda and Kia both do it this way, but the wait time differs between them, so use the number in your own manual. Watch out for hot parts around the dipstick.

6. Read the dipstick properly. Pull it out, wipe it clean, push it all the way back in, then pull it out again and read the level. It should sit between the two marks. If you can’t find a dipstick, your manual explains how your car reports its oil level.

7. Check the transmission. On many cars you can’t, and that’s normal. The Jeep Compass manual, for example, says routine fluid level checks aren’t required so the transmission has no dipstick, and a dealer can check it with special tools. If your manual lists a dipstick and a procedure, follow it exactly.

8. Look under the car. Fresh spots on the ground where you park are worth noticing, especially if a fluid keeps dropping.

What a low reading means

Brake fluid. Treat this one with respect. Mazda’s manual calls a low brake fluid level dangerous and says it could indicate brake lining wear or a leak in the system. Hyundai adds that needing frequent top-ups could indicate a leak. Topping it up doesn’t fix either problem, so have the brakes inspected.

If your manual tells you to add fluid, use the type it specifies and clean around the cap first so dirt can’t fall in. Keep it off the paint: Hyundai’s manual warns that brake fluid causes paint damage.

Coolant. Kia’s manual says frequent top-ups mean the system needs a professional inspection. Coolant shouldn’t just vanish.

Oil. Some engines use a little oil between changes, but a level that keeps dropping is worth a look. Don’t overfill it. Mazda’s manual warns that too much oil may damage the engine. Add a small amount, wait, and check again.

Be careful with coolant

Antifreeze is poisonous to people and pets. A Purdue University veterinarian notes that its sweet taste and odd color make it appealing to kids and pets, and that even a little licked off a cat’s fur could cause harm. Wipe up spills right away and store the bottle out of reach. If a pet may have swallowed some, go to a vet immediately. If a person may have swallowed some, call Poison Help at 1-800-222-1222 or 911.

Common mistakes

• Opening the radiator cap to check the level. Use the reservoir, and only with a cool engine.
• Topping up brake fluid and moving on. A low level is a warning, not a chore.
• Guessing the fluid type. Check the manual or the marking on the cap.
• Checking oil on a slope. The reading won’t be accurate.
• Overfilling. More isn’t better.
• Pouring into the wrong reservoir. Read the cap every time before you pour.
• Leaving a rag in the engine bay. Count what you took in with you.

When to hire a pro

Take the car to a mechanic if:

• Brake fluid is low, or the brake pedal feels soft
• Coolant or oil keeps dropping
• You see fresh puddles under the car
• A fluid looks milky, burnt or contaminated
• A warning light comes on for oil pressure, temperature or brakes. Your manual explains what each light means and whether it’s safe to keep driving
• Your car has a sealed transmission and you suspect a problem

Add these checks to your monthly car care checklist, along with a tire pressure and tread check. Washer fluid and wiper blades go together too. If the engine bay is too grimy to find anything, read how to clean an engine bay before you start.