Mercury Optimax Models 135, 150, Direct Fuel Injection., Page 267Get this manual
POWERHEAD
8Remove screws and connecting rod cap from piston rod assembly being installedIMPORTANT: Piston must be correctly installed and positioned as shownPistons marked with the word "UP" and with the letter "P" or "S" on top of pistonPistons with the letter "P" must be installed in the port side of engine and the word "UP" facing toward top of enginePistons with the letter "S" must be installed in the star- board side of engine and the word "UP" toward top of engine9Coat cylinder bore with 2-cycle oilMatch piston assembly with cylinder it was removed from, and position piston as described belowPush piston into cylinder14 CYL UP UP CYL S
UP CYL CYL 3
UP CYL CYL 5
2 Cycle Outboard Oil (92-826666A24)