Got some info on a possible cause for the knocking issue. Now this is not in all cases, but it is in most I guess. Ford is calling it cylinder distortion. To put it simply the piston is rocking ever so slightly inside the bore. Now is it a machining problem or bad pistons who knows. Ford does say and of course they would say this. That it will not harm engine life to have the noise, but that excessive noise should be look at asap! Their fix replace the block, the short block that is. On very loud engines that aluminium is being found during oil analyses, is do to the piston wearing excessively. Some where saying is the main bearings, but that just didn't make sense to me. Is this the true findings I don't know but, it came from a ford tech who's name I will not disclose.