Next time, a way to save some money on fluid would be use your process but instead of mixing new fluid with the old stuff use water. Water does not have the lubricity of fluid for the water pump but as long as you aren't running the engine that long it isn't going to hurt anything.

I'm with ya bcredliner. Without a doubt I'd preferred to drain the engine also but I digress. I would have just flushed it all out with several gallons of distilled water if I had it to do to over again.