Coolant Specifications: Maintenance
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Inspect cooling system every 12 months or 15,000 miles. Drain and flush cooling system every 24 months or 30,000 miles. On all models, except 4.3L Diesel, maintain a 50% mixture of ethylene glycol anti-freeze and water. On 4.3L Diesel, use 64% ethylene glycol anti-freeze and 36% water.
NOTE:
Rusty appearing coolant is an indication that coolant has become ineffective. System should be flushed and new coolant added to radiator.