Antifreeze vs. Coolant: What is the Difference and Can You Just Add Water?

What is antifreeze?

The main components of antifreeze are typically:

EG（Ethylene Glycol）、PG（Propylene Glycol）

Its main functions are:

• Preventing freezing in winter

• Raising the boiling point

• Preventing engine overheating

What is coolant?

Coolant is the liquid actually used in the engine cooling system. It is generally composed of:

• Antifreeze (ethylene glycol or propylene glycol)

• Deionized water or distilled water

• Rust inhibitor

• Corrosion inhibitor

• Anti-cavitation additive

• Anti-foam additive

The functions of coolant include:

Antifreeze protection
Heat dissipation
Corrosion protection
Scale prevention
Anti-cavitation
Water pump lubrication

What is added to engine?

For gas engines and gas generator sets: what is added is coolant, not straight antifreeze concentrate.

For example: 50% antifreeze + 50% deionized water, or a factory-premixed coolant.

Why can't just water be used in an engine?

Many users think water is cheap and just add water. However, long-term operation can lead to:

• Radiator scaling

• Cylinder liner corrosion

• Water pump wear

• Cylinder liner cavitation

• lEngine freeze cracking in winter

Especially for gas engines with long continuous operation hours, the requirements for the cooling system are higher; therefore, coolant that meets the engine manufacturer's specifications must be used.