Car coolant guides

Car coolant guides on Coolant.com cover coolant types, colours, flushes, leaks and mixing, with cited specs. You can also browse all coolant guides or use the free coolant tools.

Car coolant (often called antifreeze) is the fluid that carries heat from the engine to the radiator. It also stops the cooling system from freezing in winter, raises its boiling point in summer, and protects metals, seals and the water pump from corrosion. Choosing the right one is mostly about matching a specification, not a colour. Getting it wrong rarely causes instant damage, but over time it can shorten the life of the cooling system.

This page sums up the basics in plain language and then lists every car coolant guide on the site. For product-level detail, use the coolant directory or the find my car coolant tool. To see what a particular manufacturer specifies, start from coolant by car make.

What coolant does in your car

A water pump circulates a mix of glycol and water through passages in the engine block and cylinder head. The mix then goes through the radiator, where air carries the heat away. A thermostat keeps the engine near its working temperature, and a pressure cap lets the system run above water's normal boiling point. For a step-by-step walk-through, see how a cooling system works.

The glycol is there for freeze and boil protection. According to published engineering tables, a 50% ethylene-glycol mix freezes at about −37 °C (−34 °F) and boils at about 107 °C (225 °F) at atmospheric pressure^[1]. Plain water freezes at 0 °C and boils at 100 °C. The additive package does the corrosion-protection work. Coolants are grouped into technologies by that package: IAT, OAT, HOAT and their variants.

How to choose the right coolant

1. Read the owner's manual or the label on the reservoir cap. Carmakers name a coolant type or a spec code. For example, a 2025 Honda Accord manual specifies "Honda Long Life Antifreeze/Coolant Type 2"^[2], and a Ram truck manual calls for OAT coolant "conforming to MS.90032"^[3].
2. Match the spec code, not the colour. Several makers use similar colours for different chemistries, and dyes vary between brands. See coolant colours explained for why colour is only a hint.
3. Check for a product that states the spec. The finder lists products whose manufacturers say they meet or are approved to a given code. ASTM D3306 is the general US standard for glycol-based coolant in cars and light-duty vehicles^[4]. Meeting it alone does not mean a product meets your carmaker's spec.
4. Be careful with "universal" or "all makes" claims. Ford has published a position statement on universal antifreeze and coolants^[5]. It is worth reading before you rely on a one-size-fits-all bottle.

For the chemistry behind the labels, read coolant types: IAT to NOAT and OAT vs HOAT vs IAT. If you have a German car, see G11, G12, G13 and G48.

Premix or concentrate?

Premixed (50/50 or similar) coolant is ready to pour. Concentrate must be diluted, and carmakers set limits on how strong the mix can be. Hyundai's manual, for example, says to use "only deionized water, distilled water, or soft water" and to keep antifreeze between 35% and 60%^[6]. Some factory coolants must not be diluted further: Honda's Type 2 is "premixed with 50% antifreeze and 50% water. Do not add any straight antifreeze or water"^[2], and Tesla says of its G-48 coolant: "Do not add water"^[7]. The premix vs concentrate guide covers the trade-offs, and the freeze and boil calculator estimates the protection a given mix gives.

Topping up, mixing and changing coolant

Never open a hot cooling system. The coolant is under pressure and can spray out scalding hot. Wait until the engine is cool, then top up the reservoir to the marked level with the specified coolant. See how to add coolant. If the level keeps dropping, the cause is usually a leak or, less often, an internal fault. Read low coolant and coolant leaks, and have it checked rather than just topping up.

Avoid mixing different technologies. Ram's manual, for example, warns that its OAT coolant "should not be mixed with" HOAT coolant^[3]. The mixing checker and can you mix coolant? explain what to do if it has already happened. Change intervals vary widely by maker and coolant: some are measured in years, others are "long life" fills. Use the schedule in your manual. How often to change coolant explains how to read those schedules, and coolant flush covers the job itself.

Safety and disposal

Most car coolant is ethylene glycol, which is poisonous if swallowed. According to Poison Control, someone who swallows antifreeze may seem fine for several hours while the body breaks it down into harmful by-products^[8]. If anyone, or a pet, may have swallowed coolant, get help straight away. In the US, call Poison Control at 1-800-222-1222. Store bottles closed and out of reach, and wipe up spills. Do not pour used coolant down a drain or onto the ground. Used antifreeze can be recycled, and the US EPA has published guidance on managing it^[9]. See antifreeze poisoning and coolant disposal.

Signs your cooling system needs attention

• The temperature gauge reads higher than usual, or a coolant warning light comes on. Stop somewhere safe and let the engine cool. See coolant warning light.
• A sweet smell, or steam from under the bonnet or from the vents. This can mean coolant is leaking onto hot parts or into the cabin heater. See antifreeze smell.
• Puddles or crusty deposits around hoses, the radiator or the water pump. Look over the hoses and pump.
• Milky or oily coolant in the reservoir. Oil and coolant should never meet, so have it diagnosed promptly. See oil in coolant.

Any of these signs means you should find the cause, not just change the coolant.

Coolant by car make

Each make page quotes the carmaker's own coolant specification with a source link, and lists products that state that spec: Toyota, Honda, Ford, GM / Chevrolet, Chrysler, Jeep, Ram & Dodge, Nissan, Hyundai, Kia, Subaru, Mazda, Volkswagen, Audi, BMW, Mercedes-Benz, Volvo, Tesla.

Disclaimer: This is general information, not advice for your specific vehicle. Your owner's manual and the coolant label take priority. If you're unsure, or your engine is overheating, ask a qualified mechanic. Coolant.com is independent and not affiliated with any carmaker or coolant brand.

Confirm the specification in your owner’s manual before buying. Product examples are not a fitment guarantee.

Choosing coolant

Buying guides

Coolant colors

Problems & parts

Safety & other uses