Well, the record is 64 days. They did oil changes inflight on the running engine. https://simpleflying.com/robert-timm-john-cook-endurace-record-cessna-172/#:~

Well, the record is 64 days. They did oil changes inflight on the running engine. https://simpleflying.com/robert-timm-john-cook-endurace-record-cessna-172/#:~:text=In%201958%2C%20that%20Cessna%20172,to%20the%20Guinness%20World%20Records https://simpleflying.com/robert-timm-john-cook-endurace-reco....