Does it matter if you only flush half your coolant?

Question

For example if I were to drain my coolant once, then Re-fill, would this be okay providing the coolant is the same brand and type?

I have made a habit of doing this in the past as due to my ignorance I was unaware that draining the coolant once would only drain around 40%. The coolant does get changed regularly around 15,000 miles however as I said it’s not a full flush.

I won't be able to do several flushes to get all the old coolant out of my system until summertime as it is quiet cold at the moment where I live and filling, running the engine, allowing engine to properly cool then draining several times would take two days and I don't fancy taking the chance with cold nights. Some websites recommend it should be re-filled and drained around four times, if this is true then defiantly will take two days, if just draining and re-filling twice is enough one day should be fine.

Answer 1

I mean, it's kind of life changing half your oil I suppose; why would you go to the effort unless you're going to change it all? I would recommend flushing the whole circuit before refilling with new so you get all the gunk out.