One problem related to engine oil leaking has been reported for the 2007 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2007 Hyundai Sonata based on all problems reported for the 2007 Sonata.
Valve cover leaks onto alternator, can cause sudden power loss and premature alternator failure. I've been researching this issue and other people have had this exact thing happen. Apparently once you get the valve cover gasket fixed, it will fail again in another year or so. There is a defect either in the gasket or the valve cover mating surface. Currently my car is only at the stage of oil leaking from cover gasket and getting onto the alternator. No further failure has happened yet. My car has 67,000 miles.