the 400's that i've rode since the early 80s, well one of them, the other was in the back yard for 30 yrs until 05, its motor with what looked like less than 3000 miles on it went into the work bike frame. they both always have a pearl sheen that i used to worry about, the one that took over on 05, has (to me) a lot of blowby when the oil dipstick is opened, i ride this bike utterly hard, i don't cut it any slack, i usually shift without the clutch especially if i'm carrying home good junk that people are throwing away these days, or christmas trees, the clutch isn't strong, they aren't from the factory, it doesn't slip but i can't shift any smoother using the clutch half the time anyways, i ride it near red line 80% of the time. at change time 1500 miles to 2000 the oil level will have dropped from full to less than a half quart or half way down the crosshatch on the dipstick, and i got top end oil leaks to account for that much oil. and that's normal for hondas 4s, i had 3 750s same thing, the cases are always shiny, just wipe it off. wear white pants with white boots will show how much it leaks. the oil always has the sheen to make me think it's wearing somewhere, yet the bikes performance only slightly declines slightly until a ignition tweek or a vacuum tweek, in all the years i've had these motors i've had them apart for the weirdest reasons, carbs etc i just recent did a leak down test for the first time, and did a manometer test to set the slides, i've always done it by sound, and they were off a bit, sounded great as i got it perfect, it lasted about 2 weeks and now runs like it always has, consistently well. for a new owner of these things can and will drive you nuts to try and dial it all in. i run em and they keep running. oh the oil sheen feels like silk, i quit worrying about it, there's always tiny bits of metal, very little amount in oil changes. one of the gears on the mainshaft is notorious for pitting. and these motors are high reving masterpieces, the screens and filters work. i don't see how new owners with no huge experience in riding and working on these bikes can manage, they're very temperamental, be careful but don't baby it, give it room to run, and get a spare bike for parts.
