Knowledge Base
BMW Coolant Types Explained — Can I Mix Blue and Green?
BMW Coolant Types — Can I Mix Them?
BMW has used different coolant colors over the years, and mixing the wrong types can cause problems. Here's the definitive guide.
BMW Coolant Specifications
BMW HT-12 (Current Standard)
- Color: Blue or blue-green
- Type: Hybrid Organic Acid Technology (HOAT)
- Used in: All BMWs from ~2018 onwards
- Lifespan: 4 years or 80,000 km
BMW LC-18 (Previous Standard)
- Color: Green
- Type: Organic Acid Technology (OAT)
- Used in: BMWs from ~2000-2018
- Lifespan: 4 years or 80,000 km
Older BMW Coolant
- Color: Blue
- Type: Inorganic Acid Technology (IAT)
- Used in: Pre-2000 BMWs
Can I Mix Them?
HT-12 + LC-18: Yes, but not ideal
They're compatible in an emergency, but mixing reduces the effectiveness of both. If you mix, flush and replace with a single type at the next service.
HT-12 or LC-18 + Generic Green/Orange: NO
Generic coolants (Prestone, Peak, etc.) may not be compatible with BMW's aluminum and magnesium engine components. They can cause:
- Corrosion of aluminum parts
- Gel formation (clogs the system)
- Seal degradation
Any Coolant + Water: Only distilled water
Never use tap water. Minerals in tap water cause scale buildup and corrosion.
The Safe Choice
Just use BMW-approved coolant. It's not expensive:
- BMW HT-12 concentrate: €15-25 per liter
- Zerex G-48 (equivalent): €10-15 per liter
- Pentosin Pentofrost NF (equivalent): €10-15 per liter
Mix 50/50 with distilled water. That's it. Don't overthink it.
When to Replace
- Every 2 years or 40,000 km (our recommendation)
- BMW says 4 years — that's the maximum, not the target
- Always replace after any cooling system repair
- If the coolant looks brown, rusty, or has particles — replace immediately
