[VWNate1]

That water jacket looks nasty , a reminder why " lifetime coolant " is a myth .

The good thing is : *you* can clean it out good as new better your own self than any shop .

Use Citric Acid powder or the neat Prestone cleaner in the yellow plastic jug ~ first flush with plain water until no loose shale or red water comes out then add the cleaner and sufficient distilled water , run it to work and back a few times , not just 30 minutes idling .

I've had a few that required a week of daily commuting for over 30 minutes each way before the red crud stopped showing up in the water .

Expect the mix to turn dead black and get thick ~ this is what you want , drain , flush a few times until you can drive it 30 minutes and the water remains 100 % clear , then you can add your 60/40 % coolant mix .

The amount of time you invest here, directly correlates to how good the job turns out ~ you're cleaning up the DPO's mess , nothing you did .

Was the inside of the valley that clean or did you clean out black oily sludge ? .
Looks like you're well on the way to having a strong runner .