Radiator Flush - can you add it to coolant or does it have to be water
I'm a lurker on this forum, someday - I will get a G8, sadly one I was going to get (V6) fell through - but I think I'll hold out for a V8 to come along anyway. In the meantime, I needed a car and I ended up getting a 2004 Grand Prix GTP. It's in "decent" shape but has needed some work.
Recently, it blew the over-fill hose while I was driving it and I had to replace it, after that it started over-heating. I had the radiator flushed by a local place ($100+) and after a couple of hours he called me to let me know that I had a lower-intake manifold gasket leak...ugh.
Basically I ended up replacing the water pump, thermostat, upper/lower manifold gaskets (and I upgraded to metal ones), upper/lower radiator hoses, coolant elbows, and spark plugs/wires. Now, I've noticed a sludgey brown build up - I did switch it over to universal coolant instead of using Dex...and I suspect the previous owner did the same and caused some build-up as well. I should have flushed it again before switching coolants probably, but I just assumed since it all leaked out - was drained during the change, that it'd be alright. Somehow I noticed some sludgey build up that had been sprayed from what looks like the bottom left side of the motor but after wiping some of that off - I haven't noticed it again so I'm thinkin maybe it came from my over-filling of the resevoir? I dunno, I'll have to keep an eye on it.
Anyway - sorry for the long rant...MY QUESTION IS: I bought this Prestone Radiator Flush and it states to dump all coolant and add distilled water, then add the solution. I'm going to do the HEAVY rinse, so it says to run it 3-6 hours over a few days. Since temps are getting down to 20F, I don't feel it's safe to put water in - does anyone know if it's ok to mix this stuff with coolant or do I have to wait to flush it?