Extension in calender life

It will mainly depend on the regulations affecting your aircraft. Here in the UK as well as a certified environment we have a permit aircraft (similar to experimental) regulatory environment that allows engines to be run on condition after they have timed out in hours or calendar life. If it is a certified aircraft then you don't have this level of flexibility and you have to send your engine away for overhaul.

Some of 914 F2 serial mentioned in bulletin extended up to 15 years after verification and replacement of some important parts .

One of them is oil plugs Retrofit is important.

After that engine life extended 3 years.

That would be Service Bulletin SB-912-041-UL.