Oil leak on 2003 Pontiac Grand Prix

My car has about 31,000 miles on it, with no major problems to date. Driving is about 60% city and 40% highway at or near maximum speed limit. Noticed spots on garage floor (near front under engine)past 3-4 weeks, and oil level down about 1 qt. No warning lights have appeared on dash, no smoke or other indicators. Is this typical of loose bolts on pan....or something more serious? Thanks for your input.

Asked by for the 2003 Pontiac Grand Prix
1 answer
I would not suspect loose bolts on an oil pan. I would more think of a failed seal or gasket somewhere along the way.

The diagnostic process is a visual inspection - something may appear pretty obviously. If not, a fluorescent dye can be added to the oil, and a black light can be used to see where the leak originates.