The engine seized. It became so hard to turn had to manufacture a special tool to hold the crank pulley. Found two spun rod bearings that damaged the crankshaft beyond repair. I found the oil siphon/ oil intake filter completely clogged. The B109 must have loosened all the crud and grime in the engine. Couldn't believe how much crud was in there.

Now, rebuilding.

 

I'm sorry to hear that.
I suspected the engine being seized because I used engine flush on an old chevy lumina when i was a teenager and the same thing happened. It did such a good job loosening everything up that it killed the pump and seized the engine.

 

When you say B109, Are we talking 109WOR, known as "EPR"? I have not had one issue using it on the 5.0 motors.

 

BG109 EPR is what I had used.
Rebuilt the engine. New bearings, new rings, valves etc. Also replaced the VVT's. It ran great for the 50 miles I drove it to the dealership to get alignment, when returned to me, it was a different car. It was sluggish and the same codes are back.