1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 209Get this manual
CYLINDER BLOCKCRANKCASE
Powerhead Reassembly
Piston Ring Installation
IMPORTANT: Use caution when installing piston rings to avoid scratching piston1Install oil ring, second ring, and top ring
NOTE: "N" should face crown of piston110
4-Stroke Outboard Oil (92-828000A12)