Mike from Enderby is completely correct." 

Mike's comments run in the face of "accepted wisdom" but they are actually factual and based on science.  Far more damage occurs to an engine due to "low oil" than "old full" oil.

What Mike doesnt' mention, is that certain makes of cars seem to have engines that are more "bulletproof" than others.  The GM small-block V8 is certainly one of them, as are certain four-cylinder Toyotas, and the original Volvo four-cylinder.  These engines could run on one-half the oil level at highway speeds and suffer basically zero wear.

In my experience, LOW oil level on a medium-aged car is far more damaging, and results due to the engine seals and gaskets leaking oil between oil changes, which if left unchecked, allows oil level to drop to a lower level where engine damage occurs.

Valves get worn, piston rings wear with lower oil,  and when the oil is topped up again, the engine begins to burn and consume oil, which now compounds the problem.