In order to fully understand the original question, we need to go to the regulations concerning engine use, and what measures are in place to control the use of engines. These areas are covered in the 2010 Technical Regulations
http://argent.fia.com/web/fia-public.ns ... 6-2010.pdf
(Article 5, specifically Article 5.18)
and the 2010 Sporting Regulations
http://argent.fia.com/web/fia-public.ns ... 6-2010.pdf
(Article 28.4).
Each car is rationed to 8 engines for the course of the season's 18 races, which is just slightly more than 2 races per engine.
28.4 c) After consultation with the relevant engine supplier the FIA will attach seals to each engine prior to it being used for the first time at an Event in order to ensure that no significant moving parts can be rebuilt or replaced.
My interpretation is that the basic long block is sealed against entry, and the use of blanking plates on the exhausts restricts the team's ability to run the engine either under it's own power or via an external source in order to determine engine characteristics such as wear.
So where does that leave us? Obviously all fluids are sampled continuously for such methods as spectroscopic oil analysis. Borescopes will definitely get a work-out, as well as any other form of strict visual inspection. The name of the game is to use any and all relevant forms of non-destructive testing available.
Additionally, each and every engine of this type has every bit of it's history recorded, and available as reference. That's a lot of data, when you include all the engines that died a horrible death on the dyno. And trust me, a lot did die, many parts failed, and the teams are aware of all indications of any mechanical issues.
Just as relevant and important is the tracking of engine use, and how hard it was worked. All of this data is examined back in the factory, and compared to engineering analysis of each part in order to understand what is really going on inside the engine.
Racing should be decided on the track, not the court room.