The models in question use a forced lubrication system, with oil circulation achieved by an oil pump pumping oil from a sump under the gearbox.
The high-performance rotary pump is located in the lower part of the timing housing and is driven by the crankshaft through a helical shaft. Oil is taken in through a strainer in the sump and flows to the oil filter located at the front of the timing case. When the oil pressure reaches 4 bar, the pressure relief valve is activated.
From the oil filter, oil flows through the lubrication line to the crankshaft bearings and through the outer tube to the gearbox bearings. Through the internal channel, oil is supplied upward to the camshaft and flows to the camshaft bearings and, through the hollow axis of the rockers, to the rockers of the connecting rod bearings through the lubrication channels in the crankshaft.
After lubricating the bearings, the oil flows deep into the engine, where, by splashing or spraying, it lubricates other bearing surfaces (for example, cylinder walls, upper connecting rod heads, gears and after that the oil flows down into the sump, and the cycle begins over again.
The oil pressure switch, located in the oil sump outlet port, illuminates a warning light on the instrument panel when the oil pressure drops below 0.6 bar when the ignition is switched on. If the oil filter is clogged, the safety bypass valve located in the filter seat opens. In this case, unfiltered oil begins to flow to the bearings.