So I use my xr600 for commuting and long highway speed rides and every time I'm done riding I notice the oil level is down almost a quart at times. I check the level at fuel stops but it always seems ok. It's only after the bike sits for about 30 minutes to an hour does it show that its low. Is this normal? Is it burning oil? Or am I losing oil out of the case breather hose? Just wanna make sure I don't need to look further into engine issues. Thanks in advance.