TM 5-3810-307-24-2-1
Coolant Recommendations/Specifications
Heavy duty diesel-engines require a balanced coolant mixture of water and antifreeze. Drain and replace the
mixture every 2 years, 320,000 KM [200,000 miles] or 6,000 hours of operation (whichever occurs first) to
eliminate buildup of harmful chemicals.
Antifreeze is essential in any climate. it broadens the operating temperature range by lowering the
coolant freezing point and by raising its boiling point. Do not use more than 50 percent antifreeze in the
mixture unless additional freeze protection is required. Never use more than 68 percent antifreeze
under any condition.
Use soft water in the coolant mixture. Contaminants in hard water neutralize the corrosion inhibitor
components. Water must not exceed 300 ppm hardness, or contain more than 100 ppm of either
chloride or sulfate.
Specifications - Use low silicate antifreeze which meets ASTM4985 test (GM6038M spec.)
criteria.
Concentration - Antifreeze must be used in any climate for both freeze and boiling point protection.
Cummins recommends a 50 percent concentration level (40 percent to 60 percent range) of
ethylene glycol or propylene glycol in most climates. Antifreeze at 68 percent concentration
provides the maximum freeze protection and must never be exceeded under any condition. Antifreeze
protection decreases above 68 percent.
Ethylene Glycol
Propylene Glycol
40% = -23 C [-10 F]
40% = -21 C [-6 F]
50% = -37 C [-34 F]
50% = -33 C [-27 F]
60% = -54 C [-65 F]
60% = -49 C [-56 F]
68% = -71 C [-90 F]
68% = -63 C [-82 F]
Concentration Testing - Antifreeze concentration must be checked using a refractometer (such
as Fleetguard Part No. CC2800). "Floating ball" type density testers or hydrometers are not accurate
enough for use with heavy duty diesel cooling systems.
