The Hummer H2 uses GM Dex-Cool long-life engine coolant, an orange, organic-acid formulation designed for GM engines. It is typically mixed 50/50 with distilled water, unless you buy a premixed version. Always verify your model year and consult the owner's manual.
In this article, we look at the official coolant specification for the H2, how to mix it correctly, and practical maintenance steps to keep the cooling system in good shape on a vehicle that spans model years from 2002 to 2010. We also cover compatibility cautions and what to do if you need to switch coolant brands.
Coolant type and official guidance
The H2's cooling system was designed around GM Dex-Cool long-life coolant, an orange-colored, silicate-free OAT (organic acid technology) formulation. Dex-Cool helps protect aluminum engine components and extends service intervals compared with conventional green coolant. GM and service literature generally require Dex-Cool or a GM-approved OAT coolant and emphasize avoiding mixing with conventional green coolant. If the system currently contains a different product, a thorough flush is often recommended before refilling with Dex-Cool.
Key guidance for selecting coolant and maintaining the system:
- Use Dex-Cool or a GM-approved Dex-Cool-compatible OAT coolant. Look for labeling that confirms Dex-Cool compatibility.
- Avoid mixing Dex-Cool with conventional green or silicate-containing coolants, which can degrade protection and form deposits.
- Choose between a ready-to-use 50/50 premix or a concentrate to dilute with distilled water according to the product label; both should be compatible with GM Dex-Cool engines.
Note: Always follow the exact instructions in the owner's manual and on the coolant bottle for mixing ratios, capacity, and replacement intervals. If you’re unsure what is currently in the system, consult a mechanic or dealer before refilling.
Mixing, maintenance, and practical steps
Before you top up or replace coolant, here is a practical guide to ensure correct preparation and maintenance:
- Plan to use Dex-Cool or a GM-approved OAT coolant and prepare it as a 50/50 mix with distilled water unless you choose a premixed 50/50 product.
- Inspect the cooling system for leaks, worn hoses, and a faulty radiator cap; address any issues before refilling.
- If converting from another coolant type, perform a full system flush to remove old coolant and contaminants; never mix directly in a hot engine.
- After filling, run the engine to bleed air from the system and recheck the level when cool; top up as needed.
With proper coolant choice, mixing, and system maintenance, the H2’s cooling system should maintain reliable temperatures and corrosion protection for the aluminum components it uses.
Summary
The Hummer H2 typically requires GM Dex-Cool long-life coolant (orange), used in a 50/50 mix with distilled water unless you buy premixed. Use GM-approved Dex-Cool-compatible coolant and avoid mixing with conventional green or other non-OAT formulas. Always refer to the owner's manual or consult a qualified technician for your specific model year and service history, and consider a system flush if you’re switching coolant brands.