カタログにOHV+フラットタペットエンジンの場合Synerlec入りのHPSに以下の記述が有ります。
Protects valve trains using roller or flat tappet lifters that require added protection due to high lift/ high ramp rate camshafts.
Will synthetic oil cause my engine to leak?
Properly formulated synthetic oils will generally not cause an engine oil leak.
Synthetic oils possess a higher degree of natural solvency, which can clean and remove deposits left by previous oils.
The removal of extensive oil deposits can expose marginal or damaged oil seals, which may then leak.
If an engine currently has excessive oil consumption (i.e. greater than 1 quart / 1,000miles) the recommended course of action is to solve the oil consumption problem before switching to a synthetic.