Vehicle Care

Engine Coolant

~3min read

The cooling system in the vehicle is filled with DEX-COOL® engine coolant. This coolant is designed to remain in the vehicle for 5 years or 240 000 km (150,000 mi), whichever occurs first.

The following explains the cooling system and how to check and add coolant when it is low. If there is a problem with engine overheating, see Engine Overheating on page 10‑23.

What to Use

The coolant warning system is set for the proper coolant mixture.

With plain water or the wrong mixture, the engine could get too hot but you would not get the overheat warning. The engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant.

Use a 50/50 mixture of clean, drinkable water and DEX-COOL coolant. If using this mixture, nothing else needs to be added.

This mixture:
• Gives freezing protection down to −37 °C, outside temperature
• Gives boiling protection up to 129 °C, engine temperature
• Protects against rust and corrosion
• Will not damage aluminum parts
• Helps keep the proper engine temperature

Notice: If an improper coolant mixture is used, the engine could overheat and be badly damaged.

The repair cost would not be covered by the vehicle warranty.

Too much water in the mixture can freeze and crack the engine, radiator, heater core, and other parts.

Notice: If extra inhibitors and/or additives are used in the vehicle cooling system, the vehicle could be damaged. Use only the proper mixture of the engine coolant listed in this manual for the cooling system. See Recommended Fluids and Lubricants on page 11‑12 for more information.

Never dispose of engine coolant by putting it in the trash, pouring it on the ground, or into sewers, streams, or bodies of water. Have the coolant changed by an authorized service center, familiar with legal requirements regarding used coolant disposal. This will help protect the environment and your health.

Checking Coolant

The coolant surge tank is located in the engine compartment on the passenger side of the vehicle. See Engine Compartment Overview on page 10‑6 for more information on location.

The vehicle must be on a level surface when checking the coolant level.

Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until it cools down. If coolant is visible but the coolant level is not at or above the FULL COLD mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL coolant at the coolant surge tank, but be sure the cooling system is cool before this is done.

GMS Sierra: Engine Coolant. The coolant level should be at or above the FULL COLD mark. If it is not, there may be a leak in the cooling system.

Test yourself

A quick GMC Sierra quiz: every answer comes with an explanation and a link to the manual page.