GMC 1995 Suburban Owner's Manual page 257

I
NOTICE:
Engine damage from running your engine without coolant isn't
covered by your warranty.
If there seems to be no leak, start the engine again. See if the fan speed
increases when idle speed is doubled by pushing the accelerator pedal down.
If it doesn't, your vehicle needs service. Turn off the engine.
How to Add Coolant to the Coolant Surge Tank
I
NOTICE:
The diesel engine has a specific coolant fill procedure. Failure to
follow this procedure could cause your engine to overheat and be
severely damaged.
If you haven't found a problem yet, but the coolant level isn't at the COLD
mark, add a 50/50 mixture of clean water (preferably distilled) and a 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.)
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