Antifreeze & Coolant – Basics and Selection
How antifreeze works, which types (G11–G13) exist, how to mix correctly, and what water quality matters.
What is Antifreeze/Coolant?
Antifreeze (coolant concentrate) is usually based on ethylene glycol or propylene glycol and is mixed with water. It protects the cooling system from freezing, overheating and corrosion – thanks to inhibitors that protect metals such as aluminium, steel, copper and solder metals.
- Protection down to −35 °C (typical 50:50 mixture)
- Overheating protection by raising the boiling point
- Corrosion protection via inhibitor packages
- Cavitation and foam protection
In Brief
Type and approval must match the vehicle/OEM. Never mix different types without approval.
Types and Specifications
IAT, OAT, HOAT: Inhibitor technologies and OEM approvals at a glance.
IAT (G11)
Silicate-based, older vehicles. Good immediate protection, shorter service life.
OAT (G12/G12+)
Organic acids, long service life, aluminium-friendly. Check mixability.
HOAT (G12++, G13)
Hybrid technology (organic + silicates). Modern OEM approvals (e.g. VW TL 774-F/-G).
Important OEM Approvals
- VW TL 774 (G11–G13)
- MB 325.x, BMW N 600 69.0
- MAN 324, Ford/Volvo/GM Specifications
Water Quality
Use demineralised/desalinated water (low hardness, chloride, sulphate). Tap water can promote deposits/corrosion.
Mixing Ratios & Freezing Point
Guide values (ethylene glycol):
- 40:60 (Concentrate:Water) ≈ −25 °C
- 50:50 ≈ −35 °C (Standard)
- 60:40 ≈ −55 °C (do not increase further – reduced heat dissipation)
Never mix different technologies without approval. Top up only with matching type or ready mix.
Maintenance & Replacement
- Change intervals according to OEM (often 3–5 years)
- Check for leaks (hoses, clamps, water pump)
- Test antifreeze and pH levels
- Bleed systems properly
Frequently Asked Questions about Antifreeze
Brief and practical answers.
Can I mix G11 with G12/G13?
Concentrate or Ready Mix?
Propylene glycol vs. ethylene glycol?
Need the right antifreeze?
We support you with selection and OEM approvals – for optimal corrosion and frost protection.