The Gulfstream IV Structural Repair Manual is very specific on rivet substitution i.e.: It is not permissible to substitute a mechanical fastener in place of a solid fastener. Check all references to assure correct fastener installation.
Earlier this year, Honeywell released a Service Bulletin that introduced an improved gearbox cover and hydrodynamic carbon face seal to reduce oil leaks.
When a squawk appears intermittently, valuable clues may be left out when communicating the details. Use your Smartphone to grab the details.