Coolant should be a clean bright green or a clean bright orange color. On some newer Fords they have a bright clean gold/yellow.
According to recent studies 70% of engine breakdowns are caused by coolant system failures. Coolant, when left too long, will become acidic. The increased acidity level will eventually cause deterioration to head gaskets, hoses, seals and various other cooling system components, thus greatly increasing repair costs.
Some of the symptoms of cooling system problems can be higher operating temperatures; poor run ability, puddles under vehicle or a sweet smell inside the vehicle, or outside the vehicle, and a steamy windshield.