It's worth noting that there are at least two different nickel-plating processes that are used in engine construction.

The most common is electroplating, where an electrical current is used to deposit nickel onto the base metal. This is the same process as used in chrome plating except that a different chemical solution and metal are used (obviously)

The second method is electroless nickel plating that works by simple ion exchange. One manufacturer that uses this method with great results is Norvel. They have nickel-plated aluminum pistons that run in an anodozed aluminum bore. The result is a very light engine with a good long life.

Just to make life more interesting, there are a number of different compositions used for electroless nickel plating (ENP) and these have markedly different physical characteristics.

I don't know what method OS have been using but I know that I've used ENP on high-temperature jet-engine nozzles and even after exposure to extreme temperatures and high velocity gas-streams, I've never encountered any physical failures of the plating.

ENP has the advantage that it produces a very slightly porous layer which tends to absorb oil and produce very low levels of friction -- just what you want for engine components.