Kroil probably would work the best but its fairly expensive compared to other penetration oils I've used. I was using liquid wrench which does do a fairly good job. Another one I like is sea foam. I'd say those two work about the same. I think I'll give pb blaster a shot because its cheap and I can pick it up at my local Canadian Tire. I'll probably end up using the propane torch to get some of those screws loose along with a penetration oil. This seems to be almost a science experiment with the stuff I've tried but I haven't spent much so far.