General Motors — Filling Fresh-Water Cooling System
Maintenance
From a General Motors owner's manual covering: Carb 5.7L, MP 5.0L, MP 5.7L, MP 6.0L. Check it applies to your exact model before use.
Before you start
- More than 50% antifreeze solution can contribute to an overheating condition.
Procedure
- Make sure that all drain plugs are properly installed.
- Remove the pressure cap from the Degas Bottle.
- Fill the system with antifreeze solution until filled.
- Start the engine and operate at idle speed (1200-1500 RPM) to purge any air from the system.
- Add additional coolant into the Degas Bottle to the MAX level; when the level remains constant, install the pressure cap.
- Continue to run the engine until it reaches normal operating temperature; check the Degas Bottle level and add coolant if necessary after the engine cools.
Specs & values
- Fill with a 50/50 mixture of DEX-COOL (or equivalent meeting GM6277M) extended life antifreeze and water
Source: General Motors owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.