Measure by collected weight, the oil flow rate (Oil leakage rate (grams/5 h) (Q)). The oil flows through the valve stem seal which flows between the valve and the valve guide, and reaches the bottom of the valve guide due to gravity and differential pressure, after 5 h.
Applicability.
Intake (Int) and exhaust (Exh) valve stem seals. After long term engine lab or field testing, leakage can be remeasured