2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 172Get this manual
POWERHEAD OPERATION
Engine Lubrication System
A camshaft driven, trochoid type pump provides engine oil to all powerhead components requiring lubricationOil from the oil pan is drawn though the oil strainer and passed through spin-on type oil filter before entering the main oil galleryA pressure regulator (relief valve) is positioned between the oil pump and the oil filter to maintain the oil pressure at constant levelFrom the main gallery, oil flow is directed either through drilled internal passage or by the splash method to those surfaces requiring lubrication INTAKE VALVE END