Rgvkiwi 10 Report post Posted July 31, 2013 Hi Guys I have a new thermostat and metal housing to put in my 95 328i M Sport. All the books and instructions say used distilled water and only BMW additive. I know you "should" use distilled water in all cars but most people don't, is it really necessary to do so in these cars? And, do I really have to buy BMW radiator additive and not use off the shelf antifreeze? Cheers. Quote Share this post Link to post Share on other sites
_Matt_ 42 Report post Posted July 31, 2013 (edited) I'd either use a 50/50 mix or concentrate and deminirilised water. Best not put extra minerals in your radiator just to save a few dollars. Edited July 31, 2013 by _Matt_ Quote Share this post Link to post Share on other sites
Allanw 1051 Report post Posted August 1, 2013 (edited) I saw the specs BMW recommend for water to mix with coolant somewhere. The majority of town supplies in NZ MORE than comply, but if you're worried, find someone with tank water to fill up. I doubt many garages use distilled water! Some people also go overboard recommending stuff, but don't know what they are talking about - some have said to use RO water - DON'T - RO water is "empty" and will dissolve anything it can, like aluminium. If nothing is dissolved in it, it WILL dissolve anything it can. We have to use SS pipes here in the hospital for the RO water, otherwise things disappear - the plug hole in our sink dissolved (brass) from it, and the main cast iron drain from our workshop down to the basement sewer did too. We had to bypass it all with plastic pipes :-) The minerals in water are dissolved in it. They won't deposit them selves in the system, unless water is continually evaporating off and increases the concentrations. The town water here in Whangarei has a hardness of about 50g/m3. In the car cooling system, that would be .25 grams max, dissolved in the coolant, assuming 50/50 mix and about 10L. There are some other minerals etc, the the amounts are similar. I don't stress about it, but then I have tank water (which has minerals in anyway) PS: most of the water in Europe is hideous, and probably doesn't meet the BMW specs. It probably still gets used. Edited August 1, 2013 by Allanw Quote Share this post Link to post Share on other sites
Ultrarandom 3 Report post Posted August 1, 2013 I use the demineralised water you can get from Supercheap or Repco along with a type of coolant from Penrite I ordered in from Supercheap which is BMW approved. It's the 4 year green stuff and has a BMW rating on it but costs a lot less than BMW stuff. Quote Share this post Link to post Share on other sites
Rgvkiwi 10 Report post Posted August 1, 2013 Thanks guys. Will look in to the Supercheap / Penrite stuff. Great. Quote Share this post Link to post Share on other sites
yng_750 247 Report post Posted August 1, 2013 most tap water is ok. bore water is horrible, leaves calcium deposits and i have seen it block water galleries and cook a motor. usually if water leaves residue when washing the car dont touch it. pukekohe is bad for mineral deposits. distilled water is cheap Quote Share this post Link to post Share on other sites
