Hydraulic Roller Lifters

If new lifters are installed, add Conditioner (1052367) to engine oil. Some engines may have both standard and .010" (.25 mm) oversize lifters. Lifters are marked on the side with an "O" if oversized. The outside of lifter bore in cylinder block is also marked with an "O" if oversized. Ensure guide and retainer are installed properly. See Fig 1.

Fig 1: Lifter, Guide & Retainer Assembly

Courtesy of GENERAL MOTORS CORP.