I had a long conversation with a Guard engineer. He said that their red one is based on OAT and especially designed for aluminium blocks.
He also invited me to visit the factory (been planning to go there some time).
Now, I've poured it in 4 cars, and its been about 3,4 months - and it hurts me to report that I'm not satisfied (or educated enough for that matter).
It lost its colour in about 3 weeks, which was odd. I had some leftover in a bottle, even that went transparentish - so it has nothing to do with my system being acidic etc.
Secondly: in like 3,4 months the pH has dropped from about 10 to 8.8 (50-50 mixture). Which predicts that I might have to drain it in a couple of months. Generally, an acidic system is to blame- but again with the leftover bottle, the same.
Coming to the final point: how can they price it, being OAT based antifreeze, so low?
I really need to visit them with these questions, car and that spare solution bottle.