Flyin'Dutch'
"All changes in engine behaviour can be early indicators of impedending trouble and as such warrant to be investigated."
To take a specific example. The engine is injected, and recently zero timed. No problems found at the 50, which included a compression test and oil analysis. Are you suggesting that further investigative work should be undertaken and if so what?
How far would you go with further examination if the occurence was isolated, with no further problems with the engine.