So, would you consider this to mean my cooling system is clean enough to go ahead and start putting coolant in? Keep in mind - this is all distilled water, no coolant - so it didn't go in this color...





OR - Should I run some more Restore PLUS through?

Backstory:

I replaced my EGR cooler about a month ago. Before I did the work, I flushed it thoroughly in this order:

Filtered Tap
Filtered Tap W/ Restore
Filtered Tap
Filtered Tap
Filtered Tap W/ Restore PLUS
Distilled

Then I got to working and had an emergency job take me away for a little, and wound up taking about two and a half days before I could run again. I know, that long with some tap water even of rather high quality is ...

Since then I have been running Distilled purely, flushing just about every other day that I have been home, I have flushed it about 8 times now, each time running it for a good number of hours - as much as 11 engine hours for one of them (hadn't intended to but work called,) usually about 2 engine hours each. Each time I make sure and drain from both block positions, and I have made sure to get the heater in the loop a few times, although that's hard to do with it being summer and all.

Now the last flush and this flush have come out like above, and I am not happy about that. There IS some rust discoloration on the hose from the Radiator to the pump, but it takes some doing to get it off... I do have the coolant filter in the loop too, and have replaced it twice since...

Do I need to go ahead and run some more Restore PLUS through to try and clean rust residue again? Maybe run a single quart of VC9, so it's not doing it at full strength?

I don't want to risk clogging my oil cooler, but I also am getting wary of running so long on Distilled only... Thanks in advance for the advice guys!