How to mix BMW coolant

The main issue when mixing your BMW’s coolant is the fact that you can hardly ever get all of the coolants out of the engine. For that reason, always strive to refill with undilute BMW coolants. Once you have put in 6 liters or a gallon and a half of coolant into your vehicle’s system, add deionized water. There are other acceptable ways to do it, for example, with a mixture of 50:50 water and coolant.

Best practices when mixing BMW coolants

In some cases, if you pour too much coolant into the system of your car, you might damage it by corroding the metals used in manufacturing. Using the wrong type of coolant would also damage your engine. Make sure to always use liquids certified or approved by your car manufacturer or dealership.

In general cases, BMWs do not like running on old coolant. Some BMW models are even more sensitive on their coolant systems than most cars. To properly flush the cooling system of your BMW you need a few simple tools.

What tools do you need to flush your BMW coolant?

It is a fairly simple process, the flushing of a cooling system. You need the right tools for the job, most of which you could find in any household.

  • A simple screwdriver, depending on the type of drain plugs in your car.
  • A funnel.
  • Drain pan, the larger the better.
  • A socket wrench that would allow you to remove the splash shields under your car if there are such.
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If you lack the tools for the job, worry not, as there are many pre-made coolant flush kits available both online and perhaps in your local gas station.

Step 1: Choosing the right antifreeze.

If you care about your car’s engine you should not pick a random antifreeze and instead get a genuine BMW coolant, approved by the manufacturer. Stick to factory-recommended products. You can clearly see the recommended parameters of your car in the car manual or look it up online, as it greatly varies by model.

Step 2: Never mix tap water with your coolant. Get distilled water.

Tap water is full of bacteria and other substances that might not be harmful to us to drink, but might greatly damage your engine, coolant systems, and other parts of your vehicle. The right mix proportion you want to get with water and coolant is a 50 / 50 ratio. This is a rather aggressive mix in the hotter parts of the world, but it does a great job of protecting the engine of your BMW and lubricating the water pump.

Step 3: Do a coolant flush on your BMW engine

If you wish to flush the coolant from your car’s system, start by removing the engine block drain plug. Ensure that the location of your drain pan is where it has to be. Allow several hours to pass for your car to be as dry as possible.

Once this is done, put the drain plug where it belongs. It’s time to service the radiator of your car. Move the drain pan toward the radiator drain plug. The plug of the radiator is usually located in one of its corners. Remove it and drain the coolant from there too. Let it drain for a while and put the plug back when it’s done.

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The next thing to do is to use distilled water to clean the system by flushing it once more. Fill your system with distilled water. Pay attention to how much of the liquid your system would take. Turn the car on and press the heater button up to the maximum. Run the car’s engine until the point where it reaches the normal average temperature. Shut down the engine and drain the system once more like you did last time.

This would remove all leftovers from the coolant in your system.

Step 4: Refill the BMW’s Coolant System with new coolant

Ensure that all the drain plugs are in place before proceeding with filling the system again. A mixture of 50 / 50 distilled water and antifreeze is what we are going for. Pay attention to whether your antifreeze has been pre-mixed with water. If it was, do not add more water and simply pour it in. If it wasn’t, go for the 50 / 50 mix.

If your car has taken 10 liters of water (2.64 gallons) when you did the water flush, now pour in 5 liters of water and 5 liters of antifreeze. In case your vehicle is equipped with a blender screw, you would need to open it, if not, simply add the coolant.


Should you use a 50 / 50 mixture of water and coolant?

There are many coolants that are factory mixed with water in a 50 / 50 premix. Using a mix of 50 / 50 water and antifreeze is important, but making sure that the coolant you are using is not factory pre-mixed with water is crucial. If by any chance you mix a pre-mixed coolant with water it might weaken the effect and cause damage to your vehicle.

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Should you fully drain your system of your BMW or mix the coolants?

Most experts and BMW fans share that they would usually go for a full drain on the car’s system before pouring in more coolant. If you do not want to do that, make sure you are well aware of on what basis are the old and the new coolants made. If, for example, they are both ethylene glycol-based, you can mix them, regardless of whether one of them is green and the other one blue.

How often should you replace your coolant?

The BMW brand recommends that drivers replace the coolant in their car’s system each two to three years, especially if they are not driven as often. Furthermore, BMW recommends coolants, packed with beneficial additives to the metals used in the production of the engine. They prevent corrosion, ensure lubrication and protect the entirety of your engine and coolant system.

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Dan Gurbalov

Why do you love cars? I love the sound of most gasoline engines. I love the smell too.

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