I noticed that my oil was low the other day so i drained what I had left in there and refilled it with fresh oil to the line. Today I noticed that it was gone again. I don't have any external visable leaks but i tilted the bike towards the oil sight guage and the oil was visible in the gauge. Is this normal or do I have a blown gasket and if its not normal will it damage anything or should I do a bottom end rebuild? Thanks in advance.