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White Paper
Oct. 13, 2026
Can You Mix DLC Liquid Coolants?
Topping up, servicing, or switching coolant suppliers means old and new coolants will inevitably mix. GIGABYTE and Castrol co-validated that Castrol ON DLC PG25 remains 100% miscible with mainstream commercial propylene glycol coolants and stays stable through a 12-week closed-loop test.
Why Coolant Mixing Matters
NVIDIA Blackwell-generation AI accelerators now exceed 1,000 W TDP per chip, and rack power density has climbed from 8 to 20 kW to 100 to 240 kW. Direct liquid cooling (DLC) has become the leading thermal solution for high-density AI data centers.
Once a liquid loop is in service, coolant mixing is routine: top-ups, supplier changes, or residual fluid from factory testing. If mixing causes precipitation, corrosion, or seal degradation, the result ranges from lower cooling efficiency to leaks and downtime.
Key Findings
- 100% miscibility: In both a realistic 10:90 changeover and a 50:50 stress mix, every sample stayed clear with no phase separation, precipitation, or haze.
- Material compatibility: Metal corrosion was tested to ASTM standards on copper, brass, stainless steel, and more, along with seals and plastics including EPDM, VMQ, and FKM. GIGABYTE liquid cooling designs use only copper, stainless steel, and nickel-plated brass on wetted surfaces to eliminate corrosion risk by design.
- 12-week closed-loop field test: The mixed coolant ran for 12 weeks in a loop simulating NVIDIA GB300 Grace Blackwell Ultra. The fluid stayed clear, pH remained stable, and iron and copper levels stayed below 1 ppm.
Applied Across the GIGABYTE Liquid Cooling Portfolio
These validation standards apply across the entire GIGABYTE liquid cooling portfolio, from G4L3/G4L4 series servers and rack-scale NVIDIA GB300/GB200 NVL72 to the GIGABYTE Accelerated Deployment Unit (GADU) and DLC GIGAPOD. Enterprise customers get the same assured fluid reliability at every scale.
The full whitepaper includes physicochemical data for every mixing group, metal and non-metal compatibility results, and complete records from the 12-week test.