Performed 100-hour inspection on ENGINE during 100hr inspection. Compression: #1 70/80, #2 78/80, #3 78/80, #4 74/80. Drained oil and serviced with 7qts. Aeroshell w100 plus oil. Replaced oil filter CH48111-1, cut open old filter and inspected, no metal found. Removed, cleaned, inspected, rotated, and reinstalled spark plugs. Removed and replaced exhaust with serviceable unit. Replaced all (4) exhaust gaskets with pn: 77611. Verified MAG timing. Adjusted idle to spec. adjusted carb mixture control to spec. Tightened all oil lines. Removed and replaced EGT probe with new unit pn: 86255. R&R both #1 and #3 oil return lines with pn: STD-1821. Replaced both oil dipstick gaskets pn: 72220 and 72059. Lubricated primer and tightened carb heat cable. Work performed in reference to Cessna 172M MM and engine manufacturer OH manual. I certify that this ENGINE was inspected IAW Cessna's 172M 100hr inspection checklist and was determined to be in an AIRWORTHY condition. Approved for return to service.