Cooling System & Coolant
Follow an overheating diagnostic tree and mix the right coolant concentration for your cooling system capacity.
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When the temperature climbs
Check in order: coolant level, drive belt (for the water pump), thermostat opening, radiator airflow and fan operation, then the water pump itself. A sudden overheating usually means loss of coolant or a broken belt/pump.
- Never open the cap when hot — severe burns
- A 50/50 mix of coolant and distilled water protects from -35 °C to above 130 °C
- Coolant also prevents corrosion and lubricates the water pump
- Use the manufacturer’s coolant type (e.g. OAT, G12)
FAQ
Typically the cooling fan does not switch on, or the fan operates only when AC is requested. At speed there is enough airflow, at a standstill there is none.
50% coolant / 50% water is the general recommendation. Lower concentration freezes and boils earlier; higher concentration (>70%) actually reduces heat transfer and freezing protection.
Between 5 and 9 litres depending on the vehicle, including the expansion tank. The calculator uses your system capacity to compute the exact concentrate and water volumes.
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