Coolant is another term for antifreeze. Depending on where you live, it can also serve as a reference for a 50/50 mix of water and antifreeze.
This vehicle asset has one primary job: to cool the engine. When the day grows hot, coolant helps to prevent overheating issues from occurring.
Although most vehicles perform well under these conditions, it is still essential to know how to check BMW coolant levels.
If too much were to leak, evaporate, or burn away, significant damage could occur to the equipment.
How to Check BMW Coolant Level
Before an engine overheats or a low engine coolant level message appears on iDrive, it is easy for drivers to check on antifreeze levels. The vehicle should be parked in a safe location with parking brakes engaged. Open the hood, turn the reservoir cap counterclockwise, and observe where the floating device appears.
If you have just finished driving your BMW, it helps to let the vehicle sit for about 30 minutes to allow the engine cool.
You may not receive an accurate reading or representation of fluid levels when everything is still hot.
This initial step isn’t necessary if the vehicle hasn’t been recently driven.
Once you’ve waited the prescribed time, you can follow these steps to check how much coolant is available for the vehicle to use.
- Open the hood of the BMW.
- Locate the reservoir that holds the antifreeze. In most models, it is to the left engine as a small, dark tank, but there are variations. Check your owner’s manual if you cannot identify its location.
- Slowly turn the cap to the coolant reservoir counterclockwise. Taking this step helps to release built-up pressure that could be in the tank.
- Once the cap is removed, you’ll see a floating device appear.
- Measure where the floating device sits in the reservoir. When you have enough coolant, it should sit level with the tank’s top.
- The minimum threshold is to have the floating device’s top sitting level with the reservoir.
If your coolant levels are lower than they should be, check your owner’s manual for an appropriate antifreeze to add to the reservoir.
You can also contact your local dealership to purchase an authorized product from the parts department.
Some automotive service companies, including those that perform oil changes, sometimes top off the fluids.
You’ll need to verify that they use an appropriate product that maximizes the performance of your BMW.
When Do I Need to Add Coolant to My BMW?
All vehicles experience natural coolant depletion as time passes. If you haven’t spotted a leak underneath your car, checking the antifreeze levels about twice per year is adequate for most drivers.
If you need to go under the hood for anything, it’s still a good idea to check all your fluids to ensure everything works as intended.
When you need to add a significant amount of antifreeze to restore its levels, a coolant leak is a probable reason. You’ll want to schedule the vehicle for a service inspection as soon as possible.
Coolant comes in several different colors. The fluids authorized for BMW use are typically green or turquoise.
If the color is darker than expected, or it looks like rust, there could be a radiator problem to address.
How Do I Choose the Correct Coolant for a BMW?
When you select a coolant product at the store or online, you’ll see compatibility verbiage on the container’s label. Although each brand is a little different, the options typically are based on the vehicle’s origin country.
You can find products for American, European, and Asian vehicles that look similar, but might have different formulations that are model-specific.
It’s always wise to look for this information on product labels before putting it into the reservoir.
Each coolant variation comes with a different color to ensure drivers correctly identify the product, even if it isn’t adequately labeled.
The table below provides more information about what to expect when working with unknown coolants.
| Coolant Type | Inhibitor | Authorized Vehicles | Coolant Color |
| Inorganic Additive Technology (IAT) | Silicates | Most Older Makes and Models | Green |
| Organic Acid Technology (OAT) | Organic Acids | General Motors, Saab, Volkswagen | Orange |
| Hybrid OAT | Organic Acids and Silicates | Ford, Chrysler, Some European Vehicles | Yellow |
| Hybrid OAT without Phosphates | NAP Free | BMW, Tesla, Mini Cooper, Volvo, and others | Turquoise |
| P-HOAT | Organic Acids and Phosphates | Nissan, Honda, Toyota, Kia, Hyundai, and Asian Vehicles | Pink or Blue |
| Si-OAT | Organic Acids and Silicates | Audi, Volkswagen, Mercedes-Benz, Porsche, and others | Purple |
Although one type could be the recommended option for your BMW, other choices could provide similar protections against overheating.
If you use an alternative antifreeze, please remember to have the materials and coolant percentage reflect what the vehicle needs.
What About Multivehicle Antifreeze for a BMW?
Coolant technologies have evolved significantly over the past century. If you own an older BMW, it might be necessary to use a formula with specific additives that let the various chemistries work together to protect the engine.
Some manufacturers produce high-mileage or multivehicle antifreeze products that could be compatible with a BMW.
It depends on what the composition profile is and if the item is rated for use in your make and model.
Why Is 50/50 Antifreeze Sold Today?
The coolant’s purpose is to prevent overheating, but it provides a secondary benefit. It prevents freezing from happening for BMW drivers in colder temperatures.
If you only put water in the reservoir, it would become ice once temperatures dip below freezing. There would be no coolant available to circulate through the engine.
When antifreeze is mixed with water, it has a lower freezing point than if it were used alone. Pure ethylene glycol reaches it at 0°F, but the half-and-half option can go to -35°F and still function.
This outcome is possible because antifreeze makes it harder for the different molecules to join with each other to turn a liquid into a solid.
What If I Use Pure Antifreeze in My BMW?
When a cooling system is given pure antifreeze instead of a 50/50 option or a designated formula, it can cause two specific problems that lead to long-term maintenance issues.
- The engine starts losing its protective properties, including its anti-corrosion features.
- The vehicle becomes more prone to overheating problems.
A 100% formula lowers the heat-transfer capacity of the antifreeze by up to 35%. That could damage the engine on a hot day.
Mixing the coolant with water helps the performance additives keep flowing in the suspended mixture.
Without this approach, the items settle to the cooling system’s bottom, reducing the likelihood of achieving appropriate protection.
Leaks Are Common in Vehicles
Although coolant does evaporate or get consumed, most antifreeze products are purchased by drivers with an existing leak. If you allow it to leave your vehicle, there could be environmental damage.
There is also the risk of having the reservoir run low, causing the system to overheat or the water pump to fail.
A coolant leak also encourages drivers to add tap water to their system, which is a terrible idea. The mineralization in the liquid builds up in the radiator, eventually causing more leaks or blockages to occur.
If you need to mix a 100% antifreeze product, use distilled water to get the job done instead of the hose. It contains almost zero minerals and transfers heat better.
Check Your BMW Warranty
If you use the wrong coolant in a vehicle, some automakers will void the vehicle’s warranty. Each formula is based on the materials included with the internal systems.
Radiators are made from aluminum, but some use plastic components. If an antifreeze additive uses a plasticizer, the result could be part failure.
When you mix some coolant types together, it forms a sludge that could accelerate corrosion problems. That’s why it is crucial to use the product that the owner’s manual recommends.
What Is the Best Antifreeze to Use for BMW Vehicles?
If your coolant levels are low, the official antifreeze from BMW is the best option to use. The product works to protect all common metal types found in engines and blocks, including steel, aluminum, and cast iron.
The official BMW antifreeze contains a bittering agent to eliminate the sweetness that ethylene glycol creates, reducing the risk of accidental consumption.
It comes in a one-gallon bottle, providing the turquoise formulation. Older vehicles might need a green alternative.
Drivers with a 335i cooling system will need about two gallons of antifreeze mixture to provide appropriate services.
If you place this product in the system, use distilled water to fill it the rest of the way for the best results.
What About a Third-Party Antifreeze?
If you don’t want to use the OEM antifreeze from BMW, the best third-party coolant to try is PEAK Extended Life Blue. You can find it as a concentrate product or pre-mixed 50-50 for convenience.
It uses the Si-HOAT formula, providing service life protection for up to five years or 150,000 miles.
Since the 50-50 solution comes in a one-gallon container, you might need two to complete filling it up after flushing the system.
The advanced formula works to prevent corrosion and rust from forming on any of the cooling system components.
What Happens If I Spill Antifreeze?
Antifreeze contains hazardous chemicals. Any spills should be cleaned promptly when checking the coolant level in a BMW. Puddles are harmful to the groundwater. Even with bittering agents, consumption is especially dangerous for pets and potentially fatal for people.
My first encounter with a radiator flush involved a significant repair. I just didn’t know it at the time.
When I got my BMW, it was an older model that seemed to have been treated well, but it had a lot of miles on it. I negotiated a great deal for it, took the car home, and started the maintenance work.
That’s when I discovered that my antifreeze looked gray. There was oil in it, which means that an engine seal or gasket failed.
Thankfully, I didn’t have a crack in the engine block. The radiator came through the issue fine, but the seals had to be redone. It turned out to be a relatively inexpensive repair.
When you service your vehicle at home, it helps to capture the coolant to prevent environmental damage or exposure to possible consumption.
Clean spills immediately, contain the trash, and dispose of the materials correctly according to local rules.
In return, your BMW will get to keep chugging along.