Thanks for sharing. Excellent read and fascinating. Still leads towards Sodium and Calcium as being the main culprits along with their ability to "hold" fuel in the oil during cold engine usage (dilution).
From the link shared by the OP
“It has nothing to do with the amount of oil in the combustion chamber, or if the engine is consuming oil or not. There’s going to be oil in the upper ring zone in every properly lubricated engine. It’s a question of whether the oil in the upper ring zone has a tendency to hold fuel, or not. If the fuel mixes with the oil, and the oil creates an emulsion, if you will, where it holds the fuel in the oil, that’s where things can begin to go bad,” says Speed.
It’s perhaps this one single quote that really tells the tale of their entire testing session. Based on the information shared with them from the ORNL testing, and backed up by the discoveries they made during the EFIU test sessions, all indications point to particular detergents acting as the root of the problem.
Where we talk above about sodium being highly reactive is where they received their first clues.
“In the end, you end up with this third chemical which is neither fuel nor oil, and the octane value of this third chemical is lower than the fuel or the oil, so it is what detonates,” says Speed.
“And that’s the challenge, because when it detonates, it all burns off and then it’s gone. For example, we could run the engine in a certain way to kind of load up the ring zone with this fuel/oil/soup combination, and then make a power run. In that first power run, you’d see several knock events, especially higher magnitude knock events. Then you could instantly make a second run, and the number and magnitude of knock events would diminish. By the third run, they are all gone. The engine was consuming and burning off all of the soup of unburnt fuel and oxidized oil that was reacting together because of the detergent holding the fuel in suspension.”