Sulfamic acid cleaner for plastic overflow tanks?

[Honolulu]

Just happened on a video showing a sulfamic acid solution used for getting old yellowy-brown coolant overflow tanks back to translucent white, but there's no/insufficient info about the effect on plastic. Anyone used this stuff? What were the results?

the video:

background info:

Sulfamic acid - Wikipedia

en.wikipedia.org

 

[Bert Poliakoff]

I think the problem is the tanks get brittle and full of spider cracks so maybe cleaning them like this is last chance if a new one can't be found

 

[Stevehose]

They get stress cracks along the section that slides into the bracket and leak from there.

 

[bavbob]

Given that the stuff usually comes in a plastic container, probably no effect. The question is, what is the discoloration made of.