Which one is the coolant reservoir cap, and what is the other one????

[ur20v]

These may help....

[PREDATOR 007]

The crazy thing was that I didn't get a coolant low light, it gave me a drivetrain malfunction light. The dealer said it was because the oil temp was different than the transmission oil. I was about 3/4 gallon low.

[DXBM5]

Every 2 weeks I get a notification on the computer saying low coolent. I keep topping it up but obviously something is wrong. I cannot see a leak anywhere on the ground so any ideas what it could be?

[ur20v]

Turbo coolant lines are favorite - they leak onto the turbo heat shield- you may see some staining?

[PREDATOR 007]

Originally Posted by DXBM5

Every 2 weeks I get a notification on the computer saying low coolent. I keep topping it up but obviously something is wrong. I cannot see a leak anywhere on the ground so any ideas what it could be?

Top both reservoirs off and see what happens.

[YanoM5]

Thank you for this post! It saved me as I was putting in coolant in the wrong reservoir.

[Dumpspec]

Bumping old thread. Is it OK to add coolant to both reservoir if they are low?

[alex91]

Originally Posted by dumpm3

Bumping old thread. Is it OK to add coolant to both reservoir if they are low?

Would like to know the answer to that as well.

[josec70]

Fine to add to both reservoirs; had it done at the dealer recently.

[Craze]

Is it different coolant?

[josec70]

Originally Posted by Craze

Is it different coolant?

No; same coolant.

[MnMnM]

Originally Posted by Bönz

That would be page 195 of my owner's manual.

Bonz is correct according to my manual

[BDWonder]

Originally Posted by E90Fleet

Glad you are fixed up

Hey...so what are these 2 reservoirs actually filled with? Same liquid coolant? Or does the left and right reservoir use different liquids?
Thanks dude.

[josec70]

Originally Posted by BDWonder

Hey...so what are these 2 reservoirs actually filled with? Same liquid coolant? Or does the left and right reservoir use different liquids?
Thanks dude.

Same coolant in both; recently had these topped off at dealer.

[Db750]

Originally Posted by Bönz

See attached.

Thank you for making sure the correct information was posted in this thread. Frankly Used2B and a few other members need to delete/edit their incorrect and misleading posts in this thread as it could cause someone looking for a quick answer to put coolant in wrong hole.

[Used2be]

Originally Posted by Db750

Thank you for making sure the correct information was posted in this thread. Frankly Used2B and a few other members need to delete/edit their incorrect and misleading posts in this thread as it could cause someone looking for a quick answer to put coolant in wrong hole.

If you want more information, reading all the way to post #22 will give you verified agreement over the placement of the cooling circuit filling points. I did retract my opinion and the reasons are explained in those first 20 posts. Why would someone stop part way through a thread if they wanted to learn about the subject of the thread?

E90Fleet shows the comparison of the 2013 manual and the revised 2015 manual in his #21 and #22 posts on the first page of this thread. Good information if you wish to learn more.

[TLK]

I checked my manual and it will also confuse anybody who hasn't had BMW experience. It mentions only one tank, locates the turbo tank, but shows a close up of the engine radiator tank.

The engine coolant filler on my USA driver's left side is the same cap BMW has been using on some models since the '90's. Note, it isn't the same cap still used on current models that have a big high mounted expansion tank you can see. These are pressure release caps, they are supposed to allow blow off at a certain pressure for safety. On the F10 M5, you can't see the tank and all you get is a long filler neck, kind of like a wash/wipe reservoir filler.

The other little filler tank up close to the engine with the knurled cap is for the turbo cooling circuit.

Note: although the main coolant circuit for the engine/AC/Steering/etc has a level sensor, the turbo circuit does NOT! Yes, if you get a leak or worse a hole in the turbo circuit radiator or lines, you can bleed out all the coolant in no time flat and there will be no warning. Guess how I know this.

Both tanks take the same 50/50 diluted mixture of BMW coolant.

On USA cars, the engine radiator filler neck has no min/max level (the first car, let alone BMW, I've seen like this). This is some trick BMW NA has to get all us "rich" people to keep coming back to the dealer for stupid things. In any case, a tape measure set to 6" makes a perfect gauge to stick down the neck. If it just touches the coolant in the bottom of the neck, it's perfect.

Fortunately the turbo circuit tank has a min/max level gauge inside and it's a snap to check and fill.

STAY VIGILANT! Check these levels every couple of weeks at a minimum, especially the morning before you go out for a planned hard run. Cooling is a major Achilles' Heel of this and it's 550i brother. Remember, the turbo/intercooler coolant circuit has NO low warning! You need to fix any leaks as soon as they start.

Pictured below is the main coolant circuit cap for the engine, heater core, etc.

[Db750]

Originally Posted by Used2be

If you want more information, reading all the way to post #22 will give you verified agreement over the placement of the cooling circuit filling points. I did retract my opinion and the reasons are explained in those first 20 posts. Why would someone stop part way through a thread if they wanted to learn about the subject of the thread?

E90Fleet shows the comparison of the 2013 manual and the revised 2015 manual in his #21 and #22 posts on the first page of this thread. Good information if you wish to learn more.

Originally Posted by Used2be

If you want more information, reading all the way to post #22 will give you verified agreement over the placement of the cooling circuit filling points. I did retract my opinion and the reasons are explained in those first 20 posts. Why would someone stop part way through a thread if they wanted to learn about the subject of the thread?

E90Fleet shows the comparison of the 2013 manual and the revised 2015 manual in his #21 and #22 posts on the first page of this thread. Good information if you wish to learn more.

Please keep in mind that 98% of traffic on this forum consist of owners Google searching an answer to a simple question. They would never dream of signing up for an online car forum to argue over who should delete what posts. They want to know where to have their man servant dump the can of coolant so they can slap their M6 back into all comfort and D mode and get back to the hair dresser.

[M5Rick]

I have a 2013 model and the car handbook is wrong, the engine coolant is the one on the right.

[Seattle996]

Originally Posted by TLK

Both tanks take the same 50/50 diluted mixture of BMW coolant.

On USA cars, the engine radiator filler neck has no min/max level (the first car, let alone BMW, I've seen like this). This is some trick BMW NA has to get all us "rich" people to keep coming back to the dealer for stupid things. In any case, a tape measure set to 6" makes a perfect gauge to stick down the neck. If it just touches the coolant in the bottom of the neck, it's perfect.

Someone above wrote to fill it an inch from the top and you mentioned 6 from the top.. just curious if it matters really. My fluid is at the bottom of that pipe (Pertaining to the driver side engine coolant cap)

Got a warning on my dash that had me look. Stated:

Engine coolant level low: Top off as soon as possible. Possible engine damage. Attention: scalding hazard.

A little aggressive on the verbiage, made me nervous.. I'm assuming its correlated to that driver side tank rather than the passenger side tank, as that is above minimum.

Any thoughts? Yes, I do have a leak on the coolant lines that are common. Need to swap out the rubber hose and clamps..

[TLK]

There could be a big difference between 1 inch from the top and 6 inches. Undoubtedly there is an expansion tank or chamber somewhere since hot liquid expands in volume. If you really did fill it almost full, it would just come boiling out the relief valve in the cap or blow the cap off if it doesn't work.

My 6" measurement is based on the metric info I got out of TIS.

The warning message is a helpful message but also liability mitagator. Yes, if you open it while it is hot you can get badly burned. When you try to sue BMW to cover your medical bills, their lawyers will pose that you were warned by the car and you did not heed the warning, so BMW is not responsible. Liability mitagators are to be seen constantly here in the USA, where most of the world's lawyers live and work, and most of these type of liability lawsuits are filed.

Finally, general advice to everyone - don't be cheap or lazy about fixing cooling system problems. This is a $100k USD car, it has at least 7 radiators in two cooling circuits to cool the engine, turbos, DME ECUs and so on. This is why there are no fog lights on the F10 M5. That space is needed for airflow through radiators that other cars don't have. If you get a bad failure of a hose, pipe or connection, or even a leak in a radiator, you can start losing coolant fast enough that you not be able to drive the car. Maybe even damaged something badly. And not that much of the cooling system is visible without a lot of disassembly, so you won't just fix it by the side of the road or at home.

[Seattle996]

Originally Posted by TLK

There could be a big difference between 1 inch from the top and 6 inches. Undoubtedly there is an expansion tank or chamber somewhere since hot liquid expands in volume. If you really did fill it almost full, it would just come boiling out the relief valve in the cap or blow the cap off if it doesn't work.

My 6" measurement is based on the metric info I got out of TIS.

The warning message is a helpful message but also liability mitagator. Yes, if you open it while it is hot you can get badly burned. When you try to sue BMW to cover your medical bills, their lawyers will pose that you were warned by the car and you did not heed the warning, so BMW is not responsible. Liability mitagators are to be seen constantly here in the USA, where most of the world's lawyers live and work, and most of these type of liability lawsuits are filed.

Finally, general advice to everyone - don't be cheap or lazy about fixing cooling system problems. This is a $100k USD car, it has at least 7 radiators in two cooling circuits to cool the engine, turbos, DME ECUs and so on. This is why there are no fog lights on the F10 M5. That space is needed for airflow through radiators that other cars don't have. If you get a bad failure of a hose, pipe or connection, or even a leak in a radiator, you can start losing coolant fast enough that you not be able to drive the car. Maybe even damaged something badly. And not that much of the cooling system is visible without a lot of disassembly, so you won't just fix it by the side of the road or at home.

Appreciate the response.. I read somewhere else on the 6 inches as well, thank you for confirming. Haven't filled anything yet, just wanted to research beforehand.

I've replaced the rubber hoses and clamps for the coolant lines once already. After today's warning, I checked again and noticed one clamps leaking a bit. What a terrible design flaw. The BMW heat shield jackets they supply are simply shocking. The stock BMW crimped clamps are terrible as well. I was able to spin one by hand before replacing it.