Hi, I would like to replace the (currently blue) engine coolant in my car. MB agent could only supply red coolant, said MB no longer provide the blue one and that I’d be better off changing to red, anyway? I’m guessing it’s unlikely all the fluid in the system drains from the drain tap, no matter how long you leave it? I’ve read stories about issues with coagulation if blue and red are mixed, so was wondering if anyone had a smart way to get all the old blue coolant out, without having to flush multiple times with gallons of deionised water? A flush with tap water, is that advisable?

 

I recommend looking at https://www.owi.com/retail/brands/pe...ehicles---blue which I have used for 3+ years in my 2012 E550 Coupe and have had zero issues.


Also this is what I got back from Google Gemini when asking "Red and blue coolants whats the difference for german vehicles"

"For German vehicles, the main difference between red and blue coolant is typically the chemical composition and intended application, with red coolant often being considered a "higher-grade" option designed for newer, aluminum-heavy engines, while blue coolant is more suited for older vehicles with cast iron engines, though it's crucial to always consult your specific car manufacturer's recommendations to ensure you use the correct coolant based on your vehicle's model and year.

Key points about red and blue coolant for German cars:

Color is not the deciding factor:
While red coolant is often associated with "G12" technology, which is a high-quality coolant for aluminum engines, the color itself doesn't guarantee compatibility; always check the specific coolant type recommended by your car manufacturer.

Chemical composition:
Red coolant usually contains Organic Acid Technology (OAT) additives, which are considered better for newer engines with aluminum components, while blue coolant might use older technology with different additives more suitable for older cast iron engines.

Compatibility:
Mixing different types of coolant, even if they are the same color, can potentially cause issues in the cooling system, so always check your car's manual for the recommended coolant type.

Important points to remember:

Check your owner's manual:
Always refer to your car's manual to determine the correct coolant color and type for your specific vehicle.

Consult a dealer:
If you are unsure about which coolant to use, consult your local car dealership for guidance.

Do not mix different types of coolant without checking compatibility:
Mixing incompatible coolants can lead to harmful reactions within the cooling system."