BMW requires NAP-free coolant (nitrate, amine, and phosphate-free) to protect aluminum engine components[1]. The two BMW-approved coolants are BMW Antifreeze G48 (blue) for vehicles before 2018 and BMW HT-12 (green) for 2018 and newer models[2]. Approved aftermarket alternatives include Zerex G-05, Zerex G-48, Pentosin Pentofrost NF, and Valvoline Zerex G-48 formula[3].

Why BMW Requires Special Coolant

BMW engines have specific cooling system requirements that standard green antifreeze cannot meet[1]. Understanding these requirements prevents costly damage.

Aluminum Engine Protection

BMW engines contain significant aluminum components including the cylinder head, engine block (on some models), water pump housing, and thermostat housing[4]. Standard IAT (Inorganic Acid Technology) green coolant contains phosphates and silicates that can corrode these aluminum parts over time[4].

BMW specifies coolant that is mono-ethylene glycol which is nitrite, amine, and phosphate-free[4]. This formulation prevents:

• Aluminum corrosion and pitting
• Silicate gel formation that clogs passages
• Scale buildup in the radiator and heater core
• Water pump seal deterioration[5]

Coolant Technology Types

BMW OEM Coolant Options

BMW offers two factory coolant formulations[2]:

BMW G48 (Blue Coolant)

The blue G48 coolant has been BMW's standard antifreeze for decades and remains compatible with older models[2].

BMW HT-12 (Green Coolant)

Important compatibility note: HT-12 (green) can be used in any BMW that currently contains G48 (blue) coolant, but G48 should not be used in vehicles originally filled with HT-12[2]. The green coolant is backward compatible; the blue coolant is not forward compatible[7].

Approved Aftermarket Alternatives

Several aftermarket coolants meet BMW specifications at lower cost[3]:

Best Aftermarket BMW Coolants

The Zerex G-05 is the most readily available and affordable BMW-compatible coolant[3]. It meets ASTM D-3306 standards and contains no phosphates, providing equivalent protection to BMW OEM coolant[4].

What to Avoid

Do not use these coolant types in BMW vehicles[4]:

• Standard green IAT coolant (contains phosphates and silicates)
• Dex-Cool (GM-specific OAT coolant)
• Universal/all-makes coolants unless specifically NAP-free certified
• Any coolant containing nitrites, amines, or phosphates[1]

For more BMW maintenance information, see our BMW maintenance cost guide.

How to Check and Add Coolant

Locating the Coolant Reservoir

On most BMW models, the coolant reservoir is a small black tank located to the left side of the engine bay[1]. The exact location varies by model—consult your owner's manual if uncertain.

Checking Coolant Level

1. Park on level ground and wait at least 30 minutes for the engine to cool[1]
2. Locate the coolant reservoir (usually black plastic tank)
3. Check the floating indicator inside the reservoir
4. If the indicator sits level with the reservoir top, topping up is needed[1]

Warning: Never open the coolant cap when the engine is hot. The cooling system is pressurized and can cause severe burns[6].

Proper Mixing Ratio

BMW coolant concentrate must be mixed with distilled water (never tap water) in the following ratios[1]:

Using too much coolant concentrate (above 70%) actually reduces heat transfer capability by up to 35%[1]. Using too much water increases freezing and boiling risk[1].

Some retailers sell pre-mixed 50/50 BMW coolant, eliminating the need to dilute[6].

BMW Coolant Change Intervals

Signs your BMW coolant needs changing sooner[5]:

• Sweet, syrupy smell from the engine bay
• Coolant leaks (check expansion tank seams)[2]
• Overheating issues
• Discolored or cloudy coolant
• Visible debris or sediment in reservoir

For more BMW service guidance, see our article on where German cars can be serviced.

Key Takeaways

• BMW requires NAP-free (nitrate, amine, phosphate-free) coolant to protect aluminum engine components—standard green antifreeze is incompatible
• BMW offers two OEM coolants: blue G48 (pre-2018 vehicles) and green HT-12 (2018+, backward compatible with all models)
• Approved aftermarket alternatives include Zerex G-05, Zerex G-48, Pentosin Pentofrost NF, and Valvoline Zerex G-48 formula at significantly lower cost
• Always mix coolant concentrate 50:50 with distilled water (never tap water) and change every 2-4 years depending on driving conditions
• Green HT-12 coolant can be added to vehicles with blue G48, but blue G48 should not be used in vehicles originally filled with green HT-12

Frequently Asked Questions

Can I mix blue and green BMW coolant?

Do all BMW models require the same coolant?

Is BMW coolant really necessary, or is it just marketing?

What happens if I use the wrong coolant in my BMW?

How much does BMW coolant cost at the dealer vs aftermarket?

References

1. Scrap Car Comparison. (2025). What coolants to use in a BMW, and how to top it up.https://www.scrapcarcomparison.co.uk/blog/what-coolants-to-use-in-a-bmw-and-how-to-top-it-up/
2. F80 Bimmerpost Forums. (2020). Coolant is green and need to top it off?https://f80.bimmerpost.com/forums/showthread.php?t=1768046
3. R3VLimited Forums. (2007). Coolant alternative/upgrade to save $$$.https://www.r3vlimited.com/board/forum/e30-technical-forums/general-technical/47923-coolant-alternative-upgrade-to-save
4. MyE28 Forums. (2017). Blue or green coolant?https://forums.mye28.com/viewtopic.php?t=145513
5. Azure Chemical. (2024). What BMW Coolant Should You Use in 2024.https://azurechemical.com/blog/what-bmw-coolant-should-you-use-in-2024/
6. YouTube - BIMMERZEIT. (2020). What Special Coolant Does My BMW Take?https://www.youtube.com/watch?v=d8o-OZ6QVHY
7. X3 XBimmers Forums. (2025). Dealership filled car with blue coolant (G48) even though it originally had green.https://x3.xbimmers.com/forums/showthread.php?t=2207876
8. E90Post Forums. (2019). Substitute for BMW Blue Coolant?https://www.e90post.com/forums/showthread.php?t=1696235
9. Reddit r/e46. (2024). Coolant alternative discussion.https://www.reddit.com/r/e46/comments/1ggb0o3/coolant_alternative/