The main oil duct is located in the top part of the oil pan. The bed plate with its plane surface seals on its bottom side (the interface between bed plate and oil pan top).
http://findarticles.com/p/articles/mi_m3012/is_10_183/ai_109...

An internal combustion engine pre-lubrication system that operates before a typical internal combustion engine is started, in which engine oil inside the pre-lubrication system is rapidly delivered in advance of actual starting through the main oil duct to the internal combustion components requiring lubrication
http://www.freepatentsonline.com/6253877.html

gusca ulja vise naprezu pumpu za ulje i pri istim zazorima daju veci pritisak ulja u glavnoj magistrali
http://vw-vhs-mladenovac.forumotion.com/motori-f10/ulja-t99....

14. Pranje i čišćenje uljnih magistrala bloka nakon obrade.
(sa slikom)
http://www.bhtuning.com/showthread.php?tid=643

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