Cooling System - Antifreeze Concentration and Effects

NUMBER: 86-B-48

GROUP: 6B - Cooling

DATE: March, 1986
SUBJECT: ANTIFREEZE CONCENTRATION AND COOLING SYSTEM EFFECTS

MODELS: ALL 1500 - 3500 MODELS WITH GAS OR DIESEL ENGINES
Todays vehicles are designed to operate with a 50/50 solution of antifreeze and water for optimum cooling system performance. This 50/50 solution gives the correct cooling system balance of freeze protection, heat dissipation and corrosion protection. When cooling systems are drained for any reason it is important that the correct concentration of antifreeze be maintained. Increasing or decreasing the antifreeze concentration from the desired mix can have undesirable effects on the system. Listed here are some useful facts concerning antifreeze concentrations.

^ A 50/50 antifreeze mix increases cooling capacity about 15% over clear water.

^ Higher concentrations of antifreeze will lower the cooling capacity.
^ Maximum freeze protection is obtained at about 69% antifreeze. Higher concentrations actually raise the freeze point.

^ The freeze point of 100% antifreeze is about -8~F.

^ Engine damage from freezing due to very high concentrations of antifreeze is not likely for two reasons.

1. High concentration solutions do not freeze to a solid but become a heavy slush.

2. High concentrations of antifreeze contract rather than expand at their freezing point.

Remember: For optimum year around cooling system performance, maintain a 50/50 solution of antifreeze and water.