As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE POST OIL CHANGE INSPECTION, AN OIL LEAK WAS DISCOVERED ON THE OUTBOARD REAR CORNER OF THE LEFT ENGINE. INVESTIGATION REVEALED A CRACK OR VOID IN THE WELD ON BOTTOM OF THE OIL COOLER WHERE THE OIL LEAK ORIGINATED. REPLACED WITH NEW UNIT OPS OK.