I could not find an MSDS for liquid lightning multi purpose cleaner (that contained HCl), can you find the manufacturer on the label, HCl azeotrope is around 20% and so this is what it is normally made and sold at, it can be made up to 40% fuming HCl.
Here is what I found searching for MSDS for liquid lightning multi purpose cleaner:
http://www.greased-lightning.com/Multi-Purpose_Cleaner/Greased-Lightning-Multi-Purpose-MSDS.pdf
http://www.greased-lightning.com/Multi-Purpose_Cleaner/Greased-Lightning-Multi-Purpose-MSDS.pdf
Do you hav a little more info to find the msds.