TB 750-651
6. Antifreeze Low Temperature Protection
a. Do not add 100% antifreeze directly to radiator.
b. Use 50/50 Ethylene Glycol antifreeze to protect cooling system for temperatures
down to -34 F (-37 C). Use 50/50 Propylene Glycol antifreeze to protect cooling
system for temperatures down to -27 F (-33 C). Use 50/50 antifreeze to top off or to
refill a cooling system that requires the additional coolant for any reason.
c. Use type 60/40 blend antifreeze to protect cooling system for arctic temperatures.
CAUTION
Never mix Arctic type antifreeze with water or inhibitor. Always use
Arctic type antifreeze full strength. Water can not be mixed with
Arctic type antifreeze because water will freeze at 32 F or
0 degrees C.
d. A mixture of 60/40 Arctic type Ethylene Glycol antifreeze will provide freeze
protection down to -62 F (-52 C). A mixture of 60/40 Arctic type Propylene Glycol
will provide freeze protection down to -56 F (-49 C). Use 60/40 antifreeze to top off or
to refill a cooling system that requires the additional coolant for any reason. If antifreeze
does not meet the freeze point for Ethylene Glycol or Propylene Glycol, users should
replace it with new coolant.
7. Preventive Maintenance
During scheduled maintenance services or during climatic change service, test and
inspect the cooling system.
a. Use the combination antifreeze and Battery Tester (NSN 6630-00-105-1418) to test
for freeze protection down to -50 F (-46 C). Use this only for 50/50 blend antifreeze.
b. Test strips that meet CID A-A-51461 Type II ( NSN 6630-01-011-5039) can be
used to test for freeze protection down to -60 F (-51 C). The test strips can be used for
both the 50/50 and 60/40 blends.
c. Test for Nitrite (corrosion protection). Use the test kit CID A-A-51461 Type II
(NSN: 6850-01-154-3653) or 3-way Commercial Engine coolant test strip that tests for
Nitrite concentration. Ideal Nitrite concentration for 50/50 antifreeze/water solution is
between 1200 and 1400 ppm. If some coolants have combination of Nitrite and
Molybdate as corrosion protection additives, a minimum combined concentration of
Nitrite plus Molybdate in the prediluted coolant shall be 780 ppm. Less than 300 ppm of
Nitrite or Molybdate in the CID coolant is not acceptable. Use 3-way commercial test
strips for measuring Molybdate in the coolant.
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