IF the lube oil is bad, or is used and the equipment fails, how much do yo lose? Total cost of the shutdown, the lost production, the replacement equipment, and the repair/re-installation manpower and support (cranes, tooling, admin, support costs like scaffolding and testing and balancing and startup?
If you use the oil, then replace it earlier than the standard interval: The oil is marked "Use by" 15 months ago, right? So, if the standard interval is a two-year oil lifetime, you have nine months left. If the oil has a six month lifetime, it is now 3x oil-lives old.