In the 80s I attended a GAMTA Working Group meeting regarding JAA and engine lives. The German LBA stated that as the manufacturer recommended 2000hr or 10 years then that was all they could approve, no variation nor extension. It wasn't a question of condition more of public liability. The late Dick Stratton of CSE stated that they, with the approval of the CAA, ran the engines on their training fleet to 5,000 HR with cylinder changes at I think 1,000 HR. The problem was more with the specification of the oil as at that time multi grades were in their infancy and the specifications were based on technology that was then 50+ years old. Sadly we still suffer from such attitudes.