Worked like a champ! Be sure to wear eye protection. I got a fine spray of penetrating oil to the face. This actually happened after the hammering was done. The pressure built up in the boot when I first added grease and forced the penetrating oil to spray out in a very fine stream.
The only downside was removing the tool from the grease fitting after hammering. Was tough to remove. I followed the instructions and loosened the coupler but that did not help. I was finally able to pry off. Loosening the coupler sort of breaks the sealant on the threads so some oil then leaks out. But it is insignificant and does not appear to degrade the tool performance.
One thing that concerns me is mixing this penetrating oil and lube. This tool injects penetrating oil in the joint. The penetrating oil breaks down the hardened lube which is then forced out of the boot (in my case). When I began to add grease, penetrating oil came out of the boot. As I continued to add grease, eventually the old grease began to come out. Then I stopped. Now that I think about, did this process really get all of the penetrating oil out of the joint?
Later, I tested a mixture of lubricating grease and penetrating oil. The grease dissolved to basically nothing. I went back and added more grease to the joint to see what came out - even though I am not in love with pumping grease out of a joint boot. The grease that came out was not degraded in any way.
