we have this freightliner with a c7 cat. it has been to other shops for blowing out the O-ring on the back of the head in the oil galley. it has been replaced4 times once with a new plug. when I changed it last I lubed the O-ring before installing. lasted about 3 days 50 miles. has anyone had this happen? where do I go from here?

Daniel Ladner
Technician
Quality Car & Truck Repair
Big Rapids, Michigan, USA