However, when I used to flush out the system, I used flush chemicals until I noticed that I always had a lot of problems with the cooling system right afterwards
I use tap-water. My well water is so bad…I have some fairly sophisticated filtering that makes the tap water pretty clean.
If you’re not switching types, then the flush with water step wouldn’t be that important. But if you are, I’d do the flush. The amount of minerals left after you drain the tap water would be miniscule.
I had 1999 Chevy Malibu and when the intake manifold gasket went bad on it and I had to get it replaced, my brother and his buddy who worked on it, flushed out the radiator and then put the Prestone in it that was “approved for use in all GM models” although in the owners manual for the malibu it recommended only using “Dex-cool.”
RemcoW has it right…Just like in his Subie-roos…V-Dubs I have found take that specific type of coolant…G12… I will have too look up what and why’s of it all…and then after that I may be able to know what other type of coolants I can use…I am actually about to do a flush and get that Dexcool out of my Dub…I will buy the G12 unless I can find its chemical equivalent… Not sure what chemical properties are needed in the VW…“phosphate, non-amine type” or what not…
My 2006 Toyota calls for the first coolant change at 7 years (I drive low mileage).
I decided to change it early at 5 years.
I just drained and refilled, the old coolant looked clean and smelled like the new.
The Toyota coolant comes pre-diluted, I didn’t have to worry about residual water weakening the mix.
This made things as simple as possible, but cost a bit more ($30 for 5 years).
I had Dexcool in one vehicle, and replaced it with peak global. Sure they claim they are compatible, but my advice was to dump dexcool and go with global when it was time for a change. Sure it may work fine, but a complete flush and change is my preference.