As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, NR 1 ENGINE OIL QUANTITY FROM 10 GAL TO 4 GAL, PRECAUTIONARY SHUT DOWN NR 1 ENGINE AND ACCOMPLISHED AIR TURNBACK TO MHZ WITHOUT INCIDENT. INSPECTED NR 1 ENGINE AND FOUND OIL FILTER BOWL CRACKED. REPLACED OIL FILTER/BOWL ASSEMBLY. INSPECTED MAGNETIC CHIP DETECTOR, NO METAL FOUND. SYSTEM OPS CHECKED AND LEAK CHECKED GOOD PER MM CH 79.