I have a strong suspicion my Corsa B had the factory original coolant. My grandfather didn't drive it much and I just can't see why he'd change it on a 25km engine car.
Either way, you can imagine the situation after the likely factory original coolant sat un-circulated in the system for ten plus years. A picture is worth a thousand words.
View attachment 1013
I poured out countless such buckets. Any clean liquid I poured in would turn into... this... soon after the engine warmed up. It took a couple of months worth of flushes to get it clean-ish. Now the green coolant becomes yellow-ish and not brown, so, win? No temperature problems, so...
By the way, I did use those cleaning solutions. They didn't do anything. A water hose plugged into the system worked so much better. Of course, I flushed it with distilled water after, and then actual coolant. Rinse and repeat for I don't even know how many times. Hose water is not good for your engine, sure, but it's temporary, and certainly a million times better than whatever garbage it forced out.
The reason I'm getting into car repairs is because I don't trust mechanics. It's not that they are not skilled; it's that they get a lot of cars at a time and simply cannot afford to pay attention to detail.
Several mechanics ruined my father's car. The reason he has changed several is because each one has screwed up in some major way. His engine has been put through a lot because of mistakes. I don't reckon it has much life left in it. This post is long enough though so I won't get into stupidly long stories about incorrect oil types and molten rocker covers.
Hope you succeed! Let me know how it goes.