I am trying to clean up a crankshaft from a briggs & stratton engine.
It has aluminum melted on to it from a low oil condition and thrown
rod.

I learned that Lye can be used to safely dissolve the aluminum and not
hurt the steel. I also kind of understand that muriaic acid can do the
same thing, but if left too long it can damage the journal.

Here's the problem, I can't find Lye anywhere (home depot, walmart,
lowes, CVS) and I think its cause druggies use it for meth or something
like that.

If I can't find lye, will the muriatic acid be ok? is there another
chemical that attacks aluminum but is safe for steel?