A quarter of a century ago, most automakers used conventional (usually green) coolant/antifreeze. Note: The terms antifreeze and coolant are used interchangeably. Today, extended life coolants are used.

Coolant Dye Color. Extended life coolants are dyed many different colors (green, yellow, orange, pink, blue, gold, amber, and red). However, color is no longer an indicator of the correct type of coolant to use. The dye in the coolant helps identify if there is a leak when comparing to other fluid colors on a vehicle, but does not identify the type of coolant to add.

Types of Coolant. Manufacturers use coolant with different types of additive and corrosion inhibitors. Ethylene glycol, which is the base of many coolants, is a toxic substance. You may consider purchasing safer propylene glycol based coolant if it is approved for use in your cooling system. You can purchase the original equipment manufacturer’s (OEM) coolant at the dealer or aftermarket coolants at parts, discount, and convenient stores. Note: Always refer to the owner’s manual to be sure you add the proper coolant.

Mixing Coolant. Generally a 50% water (use distilled/demineralized water) to 50% coolant is the most common mixture for freeze and boilover protection. Coolant is also available in premixed, ready-to-use bottles. Some aftermarket coolants are formulated to mix with many different types of OEM coolants regardless of color, but check the owner’s manual first.

Checking/Adding Coolant at Recovery Tank. When checking coolant level, the engine must be cool. First, check the level in the coolant recovery tank, also known as an expansion tank. It is usually translucent with a “full cold” (or MIN) and a “full hot” (or MAX) mark or a “cold fill range”. If low, remove the cap and add the manufacturer’s recommended coolant type and mixture. Note: Keep in mind, it may be a different color.

Checking/Adding Coolant at Radiator. Second, check the level in the radiator. This requires removing a cool radiator cap and looking into the radiator. Warning: Never remove a hot radiator cap – severe burns could result. The fluid should be at or near the top. If low add the manufacturer’s recommended coolant type and mixture as needed. Reinstall the cap. Note: On some engines the pressure cap is on the coolant recovery tank.