This is Kroil. It is the best penetrating oil I have ever used and I use it frequently at work and in the shop. It is hands down the best.
Let me tell you why I did this in 2 steps. I figured that with the time I let the kroil do it's magic that the plugs would come out without any trouble. That was just my wishful thinking I guess because the first plug I tried pulling out on the first Saturday broke without even attempting to come out. It was the forward plug on the drivers side. That is the easiest one to get to of all 8 so I wasn't too concerned. My friend had bought the Lisle tool beforehand in anticipation of at least 1 plug breaking. We figured that if we had the tool we wouldn't need it, but if we didn't we would. Anyways, back to the story. I watched some you tube videos and read the instructions on the tool and it seemed like it would be easy. Here is the tool. It has 2 parts to it. The first tool is used to push the ceramic down into the plug cap. The 2nd tool then self threads into the broken piece. You then use a nut that has left handed threads and that presses the piece out of the head. Well the tool is great in theory but it does have it's flaws. The first thing I came across is that the part of the tool that self threads into the broken piece does not want to thread into the super hard material used to make the plug. I had to use a hammer and did a little hammering, then some twisting, a little more hammering and some more turning etc.... I did finally manage to get the piece out of the head and I then found the 2nd flaw of the tool. When you push the ceramic down into the sleeve it states in the instructions that you cannot push it too far because of the way the tool is designed. Well that is correct BUT it still pushes it far enough to pop off the strap of the plug and there was also little pieces of porcelain missing. I used a combination of tubes, grease, and a shop vac to get everything out of the cylinder. I also have access to a boroscope that I used to look into the cylinder. I didn't see any thing in the cylinder that concerned me so I installed the plug. This all took some time and I had been called in to work that night so I decided to call it quits for the time being. I had a lot of things going on in the two weeks following so I told him I would get back to it when I had some more time to do it. So that was how round 1 went. I had a good 2 weeks to mull it over and think about removing the other 7 plugs. Here is the Lisle tool that I used.