How Much Coolant Comes Out If I ONLY Drain the Radiator?

[shertex]

I know it's not the recommended practice....that it's ideal to drain and flush the block and the heater core....but if ALL I were to do was drain the radiator, how much coolant would come out? Car is a 1992 300D, total system capacity is about 10 quarts.

Must admit I am tempted by the simpler procedure....especially being fairly confident that I have a clean system.

Thanks.