May I know what these are? Honda cars are equipped with these as far as I know. An SAE paper: 1999-01-3468 "The Effect of 0w-20 Low Viscosity Engine Oil on Fuel Economy" was written by Honda R&D engineers. My interest in this is that the paper cited engines with "low friction" AKA roller cam followers are able to take advantage of friction modifier technologies in engine oil and hence the ability to take advantage of 0W20 and 5W20 oil.
Oh yeah, before I forget, what are slipper cam followers. This paper is really interesting thanks to Jay from the BITOG forums. He noted that the paper also commented that viscosity of engine oil to have better FC also has a lower limit. Too low and FC will suffer as well increased wear.