Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
You should trust them, because an engine can only hold so much oil, and remember, oil expands when it gets hot. If the vehicle was overfilled then once it got hot enough for the oil to expand, the excess oil has to go somewhere, so it burst seal and gaskets in order to escape and relieve pressure.
You may have blown more than one gasket/seal.