I actually just bought a 15 tooth sprocket to get better RPM on the highway. About 4k at 80kph and 5k at 100kph and so on, in fifth with 14 tooth on the front. Hope it'll also lower my oil consumption, seems like I've used like 150ml in less than 500km. I think it might be dripping out somewhere, but it also seems to be linked to highway riding? I'm not sure, I don't have a lot of data so the pattern isn't clear. I have noticed drips from the chain cover, figured it was just chain lube, but maybe oil is dripping out somewhere and mixing with the chain sludge. My biggest worry is that it's actually the output shaft seal leaking. Maybe only when the oil is warm and thus thin.