I added a little bit of g12 from my vw in the summer. Everything appears to be ok so far.

 

I was not aware that cooling system problems are common for this car. That's not good. Is that kind of thing covered under a CPO warranty? I guess I need to decide between the parts dept for coolant or the service dept to find out what is going on.

 

I've had the low coolant message for a month until the garage diagnosed a leaking thermostat housing and a leaking coolant resevoir. All's good now:-)
I changed all the hoses going from the radiator to to the resevoir too.

 

Going along the lines that the cooling system is a weak point of the car, has anyone replaced all rubber hoses in the engine? My sister's E60 just had the same exact situation as the OP, and while checking the coolant tank, I checked around and noticed that a lot of the rubber hoses in the bay were getting soft and easy to squeeze.

Also, read this thread about the possible problems with V8 cooling systems here:

https://5series.net/forums/topic/937...-huge-mistake/

 

Sorry, its not Prestone its Zerex brand that is the correct coolant

 

I would go to the service department. I had the same issue, went to BMW to try to have it topped off. They recommended I have it checked out, $140 nad an hour later (yes I got ripped off), I found out that I had to get my expansion tank replaced. Covered under my warranty and most likely under CPO.

 

FYI there is a DIY for expansion tank replacement in the DIY section. It looks extremely easy to do.