How does engine oil reach the crankshaft and camshaft bearings?

In modern engines, oil is delivered to the crankshaft and camshaft bearings through a pressurized system of internal channels.1

The process functions as follows:

• Circulation: An oil pump, typically of the gear type, draws oil from the sump and pushes it through an oil filter to remove contaminants.12
• Distribution: The filtered oil is delivered under pressure into a network of passages or channels that have been drilled directly through the engine block.12
• Bearing Supply: These passages supply the pressurized oil directly to the main bearings of the crankshaft and the camshaft.1
• Internal Routing: To reach the crankpins, oil flows from the main bearing supply through additional holes drilled into the adjacent crank throws.1

Once the oil has lubricated these components, the excess oil leaking from the crankshaft bearings is sprayed onto the cylinder walls and cams, providing further lubrication to the piston pins and valve lifters. A spring-loaded pressure-relief valve ensures the system maintains the necessary pressure for consistent flow.12