Hey Crunch...Alldata says to use the tabs when refilling...Here is what it says......Jim.........
WARNING: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator, without causing the solution to boil. Removal of the radiator cap while the engine is hot and the pressure is high will cause the solution to boil instantaneously and possibly with explosive force, spewing the solution over the engine, fenders, and person removing the cap. Under some conditions, the engine coolant is combustible.
When adding coolant, the manufacture recommends that you use GM Goodwrench DEX-COOL coolant If coolant other than DEX-COOL Is added to the system the engine coolant will require change sooner - at 50, 000km (30,000 miles) or 24 months.
Two sealant pellets GM P/N 3634621, or equivalent must be added to the radiator whenever the coolant system Is drained and refilled with fresh coolant. Failure to use the correct sealant pellets may result In premature water pump leakage. Do not add the pellets to the coolant recovery bottle since this may prevent the coolant system from operating properly.
Check the radiator drain cock to be sure that it is closed.
Check the engine drain plug to be sure that it is tight.
Premix the antifreeze with clear water (distilled water preferred) in a 50/50 ratio.
If the old coolant is being used, check it for 50/50 glycol/water mix and make sure that it is clean and clear.
Place a large top funnel in the radiator fill hole.
Slowly pour in the coolant. Refer to "Specifications" in this section for the cooling system capacity. The filling may be slowed because of the thermostat being closed.
After the cooling system is filled to 13 mm (1/2 inch) below the fill hole, start the engine and let the cooling system warm up. When the thermostat opens, the coolant level may drop. If the level drops, add coolant until the level is up to the fill hole.
Replace the radiator cap.
Check the coolant level in the recovery reservoir. Add coolant if needed.