You can't use that crap on steel - its for aluminum only. Like the last poster said, you'll want to use a bronze brazing rod on that and even then, brazing rod is for joining metal, not "filling". I'd be surprised if you could get the base metal hot enough for the brazing rod to melt without it first blowing away on you - if there are pin holes you can be sure its pretty damn thin in the surrounding area !! Good luck.

And you're not going to fill a "dime size" hole that way.