Are "radiator flush" products dodgy?

[derekjay]

I recently changed the thermostat in my MZ11, I thought I would flush the radiator while I was at it. Flushing it just with water didn't do much, the water was just vaguely orange. But with the Alkali radiator clean heaps of rust and junk came out.
So here's hoping my radiator will survive a bit longer after the flush with some proper ethylene glycol based coolant in it.

[maurice c]

I've heard that a cheapo bottle of woolies white vineger @ $1.00 or so, is good for cleaning the crap out of your radiator. I have to admit i've not tried it out yet, I know that it shifts limescale real good.

[AndyTTR]

The last time i used a cooling system flush it ate out the seals on my water pump. The pump would've probably needed replacing anyway, but the flush made it come sooner rather than later.