Mahle is also the same ones who make sub grade rings and claims them the same as "factory"
They put the wrong size top ring land in one piston of the first couple sets of Dmax race ever cast. I won that prize back in 2010.
Point is, don't throw your engine builder under a bus based on what those guys say alone.
Once had a very astound engine machinist refuse to bore a Dmax block because he didn't have the proper "diamond tipped" hone called for in his tool book. Took it to another a well known BIG shop in Columbus OH, who said sure we have that tool. Upon completion I ask to see this diamond hone, to which the tech says, "What are you talking about, I used same hone as I do on all other engines." That engine was fine, and still together today.
So is why I seriously doubt a bad hone job could cause the degree of damage you've shown. Any more than a carbon ring build up would. There is some useful info in their report, but lacks clarity and doesn't jive with the oil annalist.. Just as likely the last line, "One piston ring or several piston rings are defective"
