Stick with a commercial product and save youself possible problems.
Suggestions:
Permatex 80030 Heavy Duty Radiator Cleaner, 1 quart
BlueDevil Radiator Flush - 32 Ounce (00204)
Thoro Flush INDUSTRIAL-STRENGTH RADIATOR AND ENGINE CLEANER
Bar's Super Radiator Flush

I have had great success using these products.
"Keep your cool"
Harold


Harold
Is a restoration ever finished?