I use PB Blaster most of the time. Over the years, I've tried many penetrants. I've found that my favorite penetrant is a blue tip wrench. I know you cannot utilize heat in all situations but, anytime I can, after using PB blaster and all the other tricks and the bolt is still stuck, I break out the torch and heat the surrounding metal. I've not had one single instance where I could not get the hardware loose after hitting it with heat.

I just did this two weeks ago. I almost want to just start breaking out the torch first and forget penetrants all together as I've never had much luck with any of them.