Is it okay to mix Zerex-05 with the factory BMW coolant. I have the factory coolant in my car right now but its low and the parts store down the street from my house has Zerex-05 where as the dealership is 45 minutes away. I want to make sure it wont mess anything up to use the zerex mixed with the factory coolant. thank you!

 

Zerex says it's meets BMWs specs, but "flush all the OEM coolant first". As we've discussed before, I say, if you have to add some, go with Prestone "All Makes, All Colors".....then the next time you flush it all out, replace it all with the Prestone, That way next time you have to add some, all you have to do is go to Walmart. I'm telling you this coolant thing Is Way, overthought. There are several VW owners who require G-11 and G-12 and they switched over to Prestone and have absolutely no problems. Including my own experience with it over the last 20 years, there are entirely too many people in my BMW club that have switched over to Prestone with no problem. I think you'd be better off worrying about ethanol in gas or eating Jif instead of Skippy.

 

If its not extremely low, I would just add some distilled water. A few ounces is not going to throw the mixture off.

 

I say don't mix it. Don't change it. Just get the right coolant.