[charliev68]

Trust me…I know about MBs and rebuilding an S65 and what it involves.
At 150k I believe it is not necessary. Main bearings don’t wear down as aggressively as rod bearings.
I believe main bearing #1s are spinning because people are using too loose of a clearance in their rod bearings!
This is just my hypothesis after personally tearing down and rebuilding the s65.
This other engine is just my spare engine. I don’t think it’s necessary to replace the MBs.