I used evaporust thermocure
https://www.amazon.com/Thermocure-Coolant-Remover-Removes-Cooling/dp/B00R74I5UY/ref=psdc_15718791_t2_B00B99U088
Full disclosure this was on an antique car for different corrosion potential but removed a ton of crap from my cooling system runs about 15 degrees cooler...