Match your owner's manual spec to the coolants that list it, compare formulas side by side, and learn how to top up, flush and fix leaks. Every claim is cited to the maker's own data, from family cars to AI data-center liquid cooling.
Find my car coolantBrowse 137 coolants →Coolant is the fluid that carries heat out of your engine and releases it through the radiator. In a car it is usually a 50/50 mix of glycol and water with a small package of corrosion inhibitors. The glycol stops the mix from freezing in winter and raises its boiling point in summer. The inhibitors protect the aluminium, iron, copper and rubber inside the cooling system from rust, scale and pitting. "Antifreeze" usually means the concentrate in the bottle, and "coolant" the diluted fluid, but most people use the words interchangeably. Read the full what is coolant guide for how it works, what it is made of and when it wears out.
Coolant types are named after their inhibitor chemistry, not their colour. These are the families you will see on labels:
| Type | Inhibitors | Typical use |
|---|---|---|
| IAT | Mineral (silicate, phosphate, borate) | Older vehicles, shortest change interval |
| OAT | Organic acids, no silicate | Many modern cars, extended life |
| HOAT | Organic acids plus some minerals | Hybrid specs; check which mineral |
| P-HOAT | Organic acids plus phosphate | Many Japanese and Korean cars |
| Si-OAT | Organic acids plus silicate | Many European cars |
| NOAT | Organic acids plus nitrite | Heavy-duty diesel engines |
Each type is explained, with sources and the products that list it, on our coolant types hub. Colour is a dye chosen by each maker, so two orange coolants can be different chemistries. See coolant colours explained.
You can buy coolant from a dealer parts counter (the exact factory fluid), auto parts stores (wide choice and staff help), and online or general retailers (bulk sizes and convenience). Whatever the channel, buy on specification rather than price or colour, and compare cost per mixed litre rather than per bottle. Our coolant directory lists 137 products with each maker's own published specs and links to buy, our coolants by brand page groups them by maker, and the compare tool puts up to four side by side. For typical cost drivers, see how much is coolant.
It carries engine heat to the radiator, prevents freezing, raises the boiling point and protects the cooling system from corrosion.
Practically, yes. Antifreeze is the concentrate. Coolant is the diluted mix in your engine, usually 50/50 with water.
The one specified in your owner's manual. Match that spec to a coolant label, or use our Find my car coolant tool.
Only if they meet the same specification. Mixing different chemistries can reduce corrosion protection and shorten coolant life.
Follow your owner's manual. Intervals range from a few years for conventional coolant to much longer for extended-life types.
Distilled water is an emergency stopgap only. It dilutes freeze and corrosion protection, so restore the correct mix soon.
The questions drivers ask most, answered with specs and safety first.
Pick the spec code from your manual and see products whose makers list it.
What Toyota, Honda, Ford, GM, VW, Tesla and others specify, with citations.
Every brand in the directory: chemistries, spec codes and products.
100+ products with sourced chemistry, spec codes and service-life claims.
Up to four products side by side, with a shareable link.
Find your spec in the manual and match the label.
When to flush, flush vs drain-and-fill, step by step.
Signs, causes, how to find it, and what affects repair cost.
Why color is not a spec, and what it usually means.
Which to buy, and how to dilute correctly.
What it means and the safe steps to take.
A neutral hub for the fluids behind AI-era direct-to-chip and immersion cooling.
Sourced list of qualified suppliers and products.
The propylene glycol fluid behind direct-to-chip loops.
How the two approaches and their fluids differ.
Compare qualifications side by side.
Fast, private, no sign-up.
EG or PG, 0–60% by volume, from published tables.
IAT, OAT, HOAT, P-HOAT, Si-OAT compatibility rules.
Qualified PG25 fluids at a glance.