well, looking at what happened, and how this all started after you lost oil, its not looking good, oil has to go through the filter before it goes through the engine, and since you lost your filter, you lost oil pressure as soon as you lost the filter. it doesnt matter how much oil you had left in the pan, the only thing i could think of is the turbo went out because of low oil, and you got rod knock because of it too. i honestly dont see any other explanation. it sucks, but thats what it sounds like.