Man, I didn't think it was that great of an idea! 8% would be a deal! lol
I talked to a guy at autozone before about some kind of coolant evacuator that you plugged into the surge tank, it pulled a vacuum and sucked everything out, then you put a hose into a bucket of fresh coolant and released the vacuum, and the new coolant was sucked back in. I asked him how it was possible, of course he didn't know, but he said it was enough vacuum that the hoses would collapse in and get 99% of the coolant.
What I didn't understand, is that the block/radiator are all solid, and I told him that you can't just put it under a vacuum and suck fluid out of it. I told him that would be like wrapping my lips around a beer bottle, and sucking, and expecting the beer to just be sucked up into my mouth. It can't happen. Of course he said it works....So how can that work????