Engine Coolant
 by Jerry Gregory

    It is very important that antifreeze or engine coolant is changed every two years (four years for vehicles with long life coolant) to replenish the additives that protect the cooling system from rust, corrosion, pitting, electrolysis and foaming. Your automobile cooling system should have a concentration of 50% to 70% antifreeze to water at all times.

Vehicles using Extended Life antifreezes should be changed in about 50,000 miles or 4 years to prevent system damage. 

 

Is Antifreeze Really Important?

    Yes, but not just because of the danger of freezing. Back in the early days of Automobiles when engines were very simple and made entirely of steel, water worked OK to cool the engine, after all it was drained regularly (sometimes nightly in the winter) to prevent rust and freezing. The first antifreeze solution consisted of alcohol, which prevented freezing but was inefficient and didn’t prevent rust or corrosion. More stable and efficient solutions to prevent the coolant from freezing in the engine were soon created which were the forerunners of what we use today.

    The modern antifreeze, however, does much more. It provides year-round protection of the cooling system: It prevents freeze up in winter and boilover in summer (especially in cars with air conditioning). It provides protection from rust and corrosion and does not harm rubber hoses and plastics. A desirable antifreeze should not corrode metal parts, attack rubber, become viscous at low temperatures, or evaporate readily at the ordinary engine operating temperature. It should be chemically stable, a good conductor of heat, and a poor conductor of electricity (which causes electrolysis).

    The performance requirements of automobile antifreeze became more severe during the 1980's. The reduction of the overall mass of vehicles to improve fuel economy entailed extensive use of light materials such as aluminum and plastics for the construction of engine and cooling system parts. The volume of antifreeze used was also drastically reduced to further reduce weight, subjecting the antifreeze to high rates of flow, high temperatures and significant metal-to-coolant heat fluxes. Today's smaller, efficient and powerful engines dissipate more heat, requiring that the antifreeze keep the heat exchange surfaces in clean condition. In addition, corrosion, which in itself is of concern, can also result in heavy corrosion deposits that impedes heat transfer.

 

What is Electrolysis?

    As the additives in your coolant that keep it neutralized become depleted the coolant actually develops an electric charge from passing over dissimilar metals. You can even measure this voltage with a voltmeter! This small electric current removes metal from engine surfaces leaving large pits or holes and can eventually eat entirely through a component. It can also weld bolts and fittings to the engine and components.

A Digital Multimeter can be used to test for this.

  1. Attach the DMM ground probe to the negative battery post.
  2. Insert the tip of the positive probe into the coolant and observe the reading.

OK – less than .10 volts.
Bad – anything above .20 volts.

 

Antifreeze Concentration Chart

TEMPERATURE F.

ANTIFREEZE CONCENTRATION

WATER CONCENTRATION

32

0%

100%

25

10%

90%

20

16%

84%

15

21%

79%

10

25%

75%

5

29%

71%

0

33%

67%

-10

39%

61%

-20

44%

56%

-30

48%

52%

-34

50%

50%

-40

52%

48%

-50

56%

44%

-60

59%

41%

-70

64%

36%

-84

70%

30%

ANTIFREEZE CONCENTRATION SHOULD BE AT LEAST 50%

 

Types/Colors of Antifreeze

 

Good reasons to bring your Car, SUV or Light Truck to Wayne's Garage