The "Indestructible" Slant 6

You were flying outside the original design envelope with a turbo, so have to expect some issues. At least don't fault the designers. No engine is indestructible. Haven't you heard that M-B 300D diesels are "million mile" engines? Mine failed at 330K. Those are also turbo, and are not near as robust as people imagine. The slant has earned a reputation as one of the most dependable engines ever, but that doesn't mean they never fail. It sure is cheap to get a replacement though.