Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
Checking the coolant is a look, not a job with tools. Most vehicles have a plastic reservoir under the hood with a wall you can see through and two marks printed on it, and on a cold engine you can read the level through that wall without touching a cap. This page walks through finding the reservoir, reading the marks, and knowing what a low reading means. It does not walk through opening anything.
What this page will not do is tell you which coolant to add. Coolant chemistry is not one universal fluid — Mazda's own manual warns that a coolant other than the one it specifies 'may cause serious damage to the engine and cooling system,' and Ford's manual carries the same warning about mixing colours or types. Add coolant only after you check your own vehicle documentation. And if the level keeps returning to low, this page will not talk you through finding the leak: a level that drops again soon after you check it is a job for a repair shop, not a habit of adding more fluid.
Safety
DO NOT OPEN A CAP ON THE COOLING SYSTEM WHEN THE ENGINE IS HOT.
A hot system can release hot coolant and steam without warning. This can burn you badly.
Necessary equipment
| Item | Note |
|---|---|
| Vehicle documentation | The documentation gives the coolant type for this engine. |
| Flashlight optional | The light in the engine compartment is often low. |
| Pen and paper optional | Record the level and the date after each check. |
Specifications
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
Prepare the vehicle
Estimated 1 min to 11 min
STOP THE VEHICLE ON A LEVEL SURFACE AWAY FROM TRAFFIC.
Traffic can kill you.
- Stop the vehicle on a level surface away from traffic.<1mReport a problem with step 1, Prepare the vehicle
- Set the parking brake.<1mReport a problem with step 2, Prepare the vehicle
SET THE IGNITION TO OFF BEFORE YOU OPEN THE HOOD.
The cooling fan can start with no warning. The fan can injure your hand.
- Set the ignition to off.<1mReport a problem with step 3, Prepare the vehicle
- Make sure that the engine is cold before you continue.<1mReport a problem with step 4, Prepare the vehicle
- Read the coolant level only when the engine is cold.
- A hot engine gives an incorrect reading.
Open the hood
Estimated 1 min to 3 min
- Pull the hood release inside the vehicle.<1mReport a problem with step 1, Open the hood
- The release is usually below the instrument panel on the driver side.
THE ENGINE AND THE PARTS NEAR IT CAN BE VERY HOT.
A hot part can burn your skin. Let the engine become cool before you touch a part.
- Release the second latch below the front edge of the hood.<1mReport a problem with step 2, Open the hood
- Lift the hood.<1mReport a problem with step 3, Open the hood
- If the hood has a support rod, put the rod in its hole.<1mReport a problem with step 4, Open the hood
Read the coolant level
Estimated 2 min to 4 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
KEEP COOLANT AWAY FROM CHILDREN.
Coolant can cause sickness or death if a child swallows it.
- Find the coolant reservoir.<1mReport a problem with step 1, Read the coolant level
- The vehicle documentation shows the position for your engine.
- The wall of the reservoir is clear. Read the level through the wall.
- Look at the side of the reservoir.<1mReport a problem with step 2, Read the coolant level
- Find the two marks on the reservoir.<1mReport a problem with step 3, Read the coolant level
- Some reservoirs show the letters F and L.
- Some reservoirs show the words FULL and LOW.
- Some reservoirs show the words MAX and MIN.
- Read the level of the coolant against the two marks.<1mReport a problem with step 4, Read the coolant level
- The level is correct if the coolant sits between the two marks.
- The level is low if the coolant sits at the lower mark or below it.
DO NOT MIX DIFFERENT TYPES OF COOLANT.
A wrong mixture can damage the engine and the cooling system.
- If the level is at or below the lower mark, do not open a cap on the cooling system.<1mReport a problem with step 5, Read the coolant level
- Your vehicle documentation gives the correct coolant for your engine.
- A wrong type of coolant can damage the engine.
Close the vehicle
Estimated 1 min
- Remove your hands from the engine compartment.<1mReport a problem with step 1, Close the vehicle
- Close the hood.<1mReport a problem with step 2, Close the vehicle
- Record the date and the reading.<1mReport a problem with step 3, Close the vehicle
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- coolant reservoir
- Also called: expansion tank, overflow tank, coolant recovery tank, coolant bottle, surge tank
- engine coolant
- Also called: antifreeze, radiator fluid, coolant/antifreeze mix, green coolant, orange coolant
- radiator cap
- Also called: pressure cap, coolant cap, cooling system cap
- hood
- Also called: bonnet, the front lid, engine cover
- temperature warning lamp
- Also called: temp light, overheating light, engine temperature warning light, hot light
When to use a professional
Stop if the level returns to low again soon after this check. A repeat low level is a sign of a leak. Speak to a vehicle repair shop.
Stop if the coolant has a milky colour or has oil in it. Stop if you see coolant on the ground under the vehicle. Speak to a vehicle repair shop.
Stop if the lamp for the engine temperature gives a warning, or the engine runs hot. Do not drive the vehicle. Speak to a vehicle repair shop immediately.
This page does not give a coolant type for your vehicle. Only the vehicle manufacturer gives that. Read the documentation for your vehicle, or speak to a dealer for your make.
Keep the coolant in a closed, labelled container, away from children. Call Poison Help at 1-800-222-1222 if a child swallows coolant.
Common questions
How do I check my coolant level?
Park on level ground with the engine cold, ideally before you have driven that day. Open the hood and find the coolant reservoir — a plastic tank with a wall you can see through, usually near the radiator. Read where the coolant sits against the two marks printed on the tank, often labelled F and L, MAX and MIN, or FULL and LOW. If the coolant sits between the two marks, the level is correct and there is nothing else to do.
Why does the engine need to be cold?
Two reasons, and both matter. A hot engine is dangerous to work near, and hot coolant under pressure can scald you if a cap comes loose. A hot engine also gives a false reading, because coolant expands as it heats and the level in the reservoir rises above where it settles once the engine cools. Mazda, Ford and Honda all tell owners to check the level cold, not hot.
Should I open the radiator cap to check the level?
No. On almost every modern vehicle you can read the coolant level through the wall of the reservoir without opening anything, and that is the only method this page covers. Ford's own owner's manual puts it plainly: steam and hot liquid can come out forcefully if you loosen a cooling-system cap, even slightly, before the system has fully cooled. If you cannot see the level through the reservoir wall, that is a question for your vehicle documentation or a repair shop, not a reason to open a cap.
What coolant should I use if the level is low?
Whatever your own vehicle documentation specifies, and nothing else. Coolant is not one universal fluid — it is several different chemistries that do not mix safely, and Mazda's manual warns that the wrong type may cause serious damage to the engine and cooling system. This page will not print a colour or a product name, because the answer differs from one engine to the next, and sometimes between two versions of the same model.
The level keeps dropping. What does that mean?
It usually means a leak, not a habit of needing extra fluid. A properly sealed cooling system does not lose coolant on a normal schedule, so a level that returns to low again soon after you check it is worth a look from a repair shop rather than a repeat top-up. Adding fluid again and again treats the symptom and leaves the leak in place.
Is spilled coolant dangerous?
Yes, and it deserves the same caution manufacturers give it. The CDC's toxicology program states that ethylene glycol, the base of most antifreeze, 'can quickly cause sickness or death in humans if swallowed,' and recommends keeping it in a sealed, labelled container out of children's reach. If a child swallows coolant, call Poison Help at 1-800-222-1222 or get medical help immediately.
What is the difference between the reservoir and the radiator?
The radiator sits behind the grille and holds coolant under its own cap. The reservoir is a smaller plastic tank, usually to one side, that gives the coolant room to expand and lets you read the level without touching the radiator at all. Some manufacturers call the reservoir an expansion tank, an overflow tank or a coolant recovery tank — they are all the same idea, and this page only asks you to look at that tank.
Related procedures
- Choose and change windscreen washer fluid before freezing weather
- How to check your engine oil and work out what oil your car takes
- How to change the engine air filter in your car
- What the red brake light on my dashboard means and whether I can keep driving
- Check an automatic transmission fluid level, or establish that the transmission is sealed and has no dipstick
- What does the oil pressure warning light mean, and is it the same as the low oil light?
- How to change the cabin air filter in a car when the air conditioning smells or barely blows
- How to find your car's maintenance schedule and record what maintenance is actually due
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Inspecting Coolant Level
- Tier 1Engine Coolant Check
- Tier 1Winter Weather Driving Tips: Prepare Your Vehicle
- Tier 1How to Check Coolant
- Tier 1Ethylene Glycol and Propylene Glycol Toxicity: Patient Education Card
Revision history
Current version 1 · updated 2026-08-04 · next review due 2027-08-04
- v1 · 2026-08-04First draft. Scope is reading the level through the reservoir wall against its marks, cold engine only, with no cap opened at any point. Every per-vehicle value publishes as consult-the-documentation: the coolant type and chemical compatibility, the volume between the marks, the freeze-protection concentration, and the coolant change interval. The reservoir-reading method rests on Mazda's owner's manual, corroborated by Subaru's own guidance to read the level in the reservoir under the hood. The hot-system hazard and the never-mix-coolant-types notice rest on both Mazda's and Ford's owner's manuals. NHTSA's winter driving guidance is the source the backlog entry itself named, and it is why the page routes coolant type to the manufacturer rather than naming one. The child-poisoning hazard rests on CDC/ATSDR's ethylene glycol patient education material.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.