Coolant Mixing Guidelines
In general, mixing different coolants in a storage tank is strongly discouraged, as it risks chemical reactions that compromise performance and damage equipment. Most coolants fall into two main categories:
Ethylene glycol-based (common in automotive and industrial systems) and Propylene glycol-based (used where toxicity is a concern). Blending these can break down additives, forming sludge or gel that clogs filters, hoses, and heat exchangers.
Important Warning
Even within the same base type, formulations vary—some contain silicates for aluminum protection, others use organic acid technology (OAT) or hybrid additives. Mixing these may neutralize corrosion inhibitors, reducing the coolant's ability to prevent rust or scale.
Key considerations about coolant mixing:
- Color is not reliable: Manufacturers use dyes arbitrarily, so two green coolants could still be chemically incompatible
- Emergency situations: If mixing is unavoidable, flush the entire system afterward with water and refill with a single type
- Compatibility checks: Always consult the manufacturer's guidelines or test a small mixture sample first
- Best practice: Store and use one coolant type per tank, clearly labeled to prevent cross-contamination
The safest practice is to maintain single-coolant systems to avoid costly repairs and ensure optimal thermal conductivity and protective properties.