Here’s a neat product from Merlin Motorsport.

The ‘go-to’ coolant additive when the temperature gauge starts rising is Red Line Water Wetter. While the name sounds a bit odd, it’s one of Merlin’s best-selling fluids and racers swear by it.

Water Wetter improves the ability of coolant to wet heat transfer surfaces by up to 50 per cent. Basically, this provides better coolant contact in the cylinder head and reduces head temperature by up to 12°C. It improves heat transfer to the metal of the engine and doubles the wetting ability of the water.

Works best in a total water cooling system but can be used with glycol anti-freeze/water mix, though this does reduce its cooling ability. Red Line Water Wetter also reduces rust and corrosion and lubricates the water pump.