Modelling engine wear and WEP limitations

[Seadog]

In Nov 1940, the Merlin XX was given "official" approval to use 12lb/3000rpm but strip inspections were not required after its use:


The Merlin 60 series engines were cleared for 15 and 18lb boost for combat and again strip inspections were not required after use:


An oil filter check was recommended, which probably took about 10mins.

The above data is from the Spit 9 Pilot's notes and from a Merlin 60 series maintenance manual.