In the realm of maintenance policies, opportunistic maintenance may sound like an outsider. Indeed, recently, looks have been focused on Reliability-Centered Maintenance (RCM), Total Productive Maintenance (TPM) and predictive maintenance or even prescriptive 4.0 maintenance as most up-to-date common good practice, but it would be a mistake to overlook the benefits of opportunistic maintenance. Good news: implementing opportunistic maintenance is perfectly compatible with these policies under certain conditions. The principle is of the simplest: consider each asset stoppage as an opportunity for preventive maintenance, and make value out of the production interruption by performing preventive maintenance actions during the system stoppage.