Lexiyntax - The vast majority of the time, when valves clearances become out of spec from useage, it is too much gap. The problems that arise from that are that the follower doesn't follow the cam profile and the opening ramp up becomes less of a ramp up, and more of a slam up. Which furthers wear and increases noise. And, since the valves won't push open as far, a bit less power too.
But there shouldn't be any way to affect the oil with an out of spec valve clearance.
2016 Honda Rebel 250 - The "Piglet."
AFR sensor equipped and downsized to a 0.105" main jet.
The only changes so far.
Bought on 6/29/19 with 44 miles.