Buick 1993 Skylark Owner's Manual page 201

How to Add Coolant to the Coolant Surge
Tank
If you haven't found a problem yet, but the coolant level
isn't at or above "FULL COLD," add a 50/50 mixture of
clean water (preferably distilled) and the proper
antifreeze at the coolant surge tank, but be sure the
cooling system, including the coolant surge tank
pressure cap, is cool before you do it. (See "Engine
Coolant" in the Index for more information about the
proper coolant mix.)
/I\
CAUTION:
Steam and scalding liquids from a hot cooling
system can blow out and burn you badly. They
are under pressure, and if you turn the coolant
surge tank pressure cap
--
even a little
--
they can
come out at high speed. Never turn the cap when
lhe cooling system, including the coolant surge
tank pressure cap, is hot. Wait for the coolin-
system and coolant surge tank pressure cap
1 3
cool if you ever have to turn the pressure cap.
t