Chevrolet 2003 Blazer Owner's Manual page 297

4. Then fill the coolant recovery tank to ADD mark.
5. Put the cap back on the coolant recovery tank, but
leave the radiator pressure cap off.
6. Start the engine and let it run until you can feel the
upper radiator hose getting hot. Watch out for the
engine cooling fan.
7.
By this time, the coolant level inside the radiator
filler neck may be lower. If the level is lower, add
more of the proper DEX-COOL@ coolant mixture
through the filler neck until the level reaches
the base of the filler neck.
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