I've had her parked on the side of the house for a few years and noticed some dark and sludgey oil(the light stuff) under the seat. My brother in law thought it would be a cracked oil tank or seal, but it doesn't appear to be leaking anywhere around it. I can't remember it running bad last time I was out so I'm hoping it is nothing major. If it is a leak in the oil line would it be so dark and sludgy after sitting for a long time? Any thoughts?