Engine coolant

Summary

Source: owner's manual / last verified 2026-10-16 (2018 GMC Terrain owner's manual, cooling system and capacities (opens in a new tab)).

Safety

• An underhood fan can start when the engine is off. Keep hands and tools clear.
• Do not touch hot hoses or open the system while the coolant is boiling.
• Do not run the engine if coolant is leaking.

Symptoms

• Check whether coolant is visible in the surge tank. If the coolant in the tank is boiling, wait until it cools.
• A 5-year or 150,000-mile sentence was not in the Terrain coolant pages that were read. This page does not copy the Cruze sentence.

Diagnosis

1. 1.5L L4 gas (LYX), all-wheel drive: 6.6 L (7.0 qt).
2. 1.5L L4 gas (LYX), front-wheel drive: 6.6 L (7.0 qt).
3. 2.0L L4 gas (LTG), all-wheel drive: 7.8 L (8.2 qt).
4. 2.0L L4 gas (LTG), front-wheel drive: 7.8 L (8.2 qt).
5. 1.6L L4 diesel (LH7): 7.5 L (7.9 qt).
6. Use a 50/50 mixture of clean, drinkable water and only DEX-COOL. The mixture gives freezing protection down to −37 °C (−34 °F).
7. Plain water or the wrong coolant can overheat the engine without the expected warning. The book says anything else can cause damage not covered by the warranty.

Tools

• Funnel

  For a cold top-off of the 50/50 mix. Do not open a hot cap.

• Clean rag

  For coolant spilled while checking the tank.

Specifications

Steps

1. 01Identify the engine

   1.5L L4 gas (LYX), all-wheel drive: 6.6 L (7.0 qt). 1.5L L4 gas (LYX), front-wheel drive: 6.6 L (7.0 qt). 2.0L L4 gas (LTG), all-wheel drive: 7.8 L (8.2 qt). 2.0L L4 gas (LTG), front-wheel drive: 7.8 L (8.2 qt). 1.6L L4 diesel (LH7): 7.5 L (7.9 qt).

2. 02Use only the printed mixture

   50/50 clean, drinkable water and DEX-COOL. Freezing protection down to −37 °C (−34 °F). Do not add anything else.

3. 03Look before you open the cap

   If coolant is visible and the level mark is not, add the 50/50 mix only after the tank has cooled. If it is boiling, wait.

4. 04Do not invent a drain procedure

   No drain-bolt torque is printed here. A 5-year or 150,000-mile sentence was not in the Terrain coolant pages that were read. This page does not copy the Cruze sentence.

Common mistakes

• Pouring one engine's coolant quarts into a different engine.
• Using plain water.
• Opening the surge tank while the coolant is boiling.

Parts and tools

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• Part

  DEX-COOL coolant

  50/50 with clean, drinkable water. The lubricants table says use only DEX-COOL.

  2018 Terrain recommended fluids (opens in a new tab)Search Amazon.com (affiliate link) (opens in a new tab)As an Amazon Associate I earn from qualifying purchases.

• Tool

  Funnel

  For a cold top-off of the 50/50 mix. Do not open a hot cap.

  McMaster-Carr funnels (opens in a new tab)

• Tool

  Clean rag

  For coolant spilled while checking the tank.

  McMaster-Carr shop towels (opens in a new tab)

Questions

Sources

• 2018 GMC Terrain owner's manual, cooling system and capacities (opens in a new tab). General Motors. Published 2017-09-15. Read 2026-10-16.

Checklist and email notes

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Other repairs on this 2018 Terrain

All GMC Terrain repairs

This repair on other vehicles

These guides cover the same kind of work. Their numbers belong to those vehicles, not to this one.