I certainly would NOT use it full strength. Dilute it at least 20:1 with water (always add the acid to the water, not the water to the acid.) That will give you 5% strength.
But, it's better to get stuff at the parts house designed for cleaning radiators.
Muriatic - Hydrocloric - HCL is used for etching and dissolving aluminum and brass. Is that what you want - to dissolve the tubes?
Before using it, run a cleaner through it. HCL will not dissolve grease or oil.
Full strength works great to eat rust away - it removes the oxygen from the ferric oxide (rust), then the iron particles from the rust falls off as a black powder.
You have to neutralize it - even if you rinse it good. If any is left on, it will promote corrosion. Use lots of baking soda mixed with a little water.
I had a seat track that was very badly rusted - I soaked it in HCL for about an hour, rinsed it, neutralized it - almost as good as new.
Wear eye protection!!!!!!! Dangerous stuff!