This is a photo of a BigSert repair on an R60/5 cylinder stud (upper left stud, left cylinder). Repaired a pulled earlier "helicoil" repair on that stud.
The 10x1.5 BigSert has an OD of 0.545" and needs a hole tapped for M12x1.5 .
The /5 uses aluminum base gaskets and sealant, so this was not an oil flow/leak issue. I disremember what the later model o-rings sizes are.