eighty6gt

http://www.babcox.com/editorial/ar/eb110242.htm

In here you'll find info on plateau honing, a technique that's been used by the OEMs for some time.

In a nutshell, cylinder walls were once honed in such a way that the "crosshatch" or scratches (necessary to hold oil for hydrodynamic lubrication at mid stroke regions) had sharp peaks. These peaks had to be knocked off by the piston rings themselves during break-in. This gave the oil, on which the rings rode, a flat surface to adhere to. Basically a plain bearing.

Unfortunately, ring wear was excessive during this process. Due to increasing emissions regs and customer expectations, it was natural to develop a process that could knock the peaks off the scratches at the factory. This is plateau honing.

So, except for minor variations, all of the "hard work" that used to be done during break in is already accomplished when you get your car. The pistons are already riding on the flat bearing surfaces with the oil holding valleys between them.

Hungry for more?

http://virtual.vtt.fi/inf/pdf/tiedotteet/2002/T2178.pdf