Coolant

Coolant circulates through a liquid-cooled engine, carries heat to the radiator and keeps the engine at a steady operating temperature. It is usually a mix of glycol (antifreeze) and water, which also protects against freezing, corrosion and boiling.

Use a silicate-free coolant made for aluminium engines. A pre-mixed product or a 50/50 dilution typically protects down to about −35 °C. Check the level in the expansion tank with the engine cold and change the coolant every 2–3 years or as the manual says.

Never open the radiator cap on a hot engine – the system is under pressure and scalding coolant can spray out. Glycol coolant is often banned on race tracks because it makes the surface slippery; plain water or a dedicated race coolant is used there.