Weeds, I've used the Kroil on badly frozen 46 engine but I was in no hurry. All in all it took me 6 weeks but it freed up..... but, I had one that after weeks of Kroil, marvel mystery, half this and half that I ended up pulling the heads and taking a piece of firewood and hitting the tops of the pistons to finally break it loose....... depending on how bad one is stuck, and the product used is what everyone things is the best!!
