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.

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.