The correct coolant is essential for protecting the cast iron block, cylinder head, and the copper and brass radiator core from internal corrosion, frost damage, and overheating. The XPAG and XPEG engines use a cast iron block and head with a copper and brass radiator, a combination of dissimilar metals that is particularly vulnerable to galvanic corrosion if the coolant's inhibitor protection is allowed to deteriorate.
Coolant Selection
A purpose-formulated long-life coolant offers the most comprehensive protection for the TD and TF cooling system. Forlife coolant is a time-proven formulation that provides simultaneous summer cooling and winter frost protection in a single ready-to-use product that does not require dilution. Its formulation offers effective heat transfer for reduced engine running temperature, anti-foaming properties with a high boiling point up to 180 degrees Celsius, and corrosion inhibitor protection that forms a barrier against internal corrosion across the entire cooling circuit. The frost protection extends down to minus 42 degrees Celsius, more than adequate for any UK winter and for the majority of climates worldwide where TD and TF cars are used.
Corrosion Protection and Head Gasket Monitoring
A distinctive feature of Forlife coolant is its built-in pH indicator, which changes colour in the presence of corrosive gases, providing an early warning of head gasket deterioration before it progresses to full failure. On the XPAG and XPEG engine, where the cylinder head gasket exists in three model-specific variants and correct sealing is critical, this early-warning function is particularly valuable. The coolant also extends the service life of rubber cooling hoses by reducing the chemical degradation that causes hose deterioration from the inside, and remains effective for ten years or more without requiring replacement, a significant practical advantage for cars that may cover relatively low annual mileages but remain filled with coolant year-round.
Conventional Antifreeze
For owners who prefer a conventional antifreeze approach, Castrol antifreeze is available in a concentrated form that is mixed with water to the required protection level, a 3:1 mix of water to antifreeze provides protection down to minus 17 degrees Celsius. Conventional antifreeze should be drained and renewed annually or every two years, as its corrosion inhibitor additives deplete over time. Both the TD's non-pressurised system and the TF's pressurised system are compatible with all coolant types available.
Draining and Filling
The cooling system is drained via the radiator drain tap at the base of the radiator and a separate drain tap on the engine block. Both taps should be opened when draining the system to ensure complete evacuation, the block drain alone will not empty the radiator, and vice versa. When refilling, the system should be filled slowly with the heater tap (if a heater is fitted) open and the engine run to operating temperature to purge air locks. Air trapped in the system will cause localised hot spots and inaccurate temperature gauge readings.
The total cooling system capacity on both the TD and TF is approximately one and a half imperial gallons.