The integral oil galleries direct the oil pump output through the external oil cooler and filters, to the main oil gallery and to drilled passages in the crankcase webs which supply oil under pressure to each main bearing. In the crankcase, five integral webs plus front and rear bulkheads support the crankshaft in seven main bearings.
An improved cylinder block has replaced the former block on all Series 60 engines. This change took effect with unit serial number 6R210293, built November 30, 1994. The former cylinder block was used on engines built prior to this serial number.
The Series 60 cylinder block was further improved by the addition of a drilled lubrication orifice and bolt hole at the base of each cylinder bore. The orifices are drilled into the main oil gallery and are required for installation of bolt-on oil spray nozzles used with forged steel pistons on premium engines. When blocks are used for non-premium engines with cast-iron pistons, the lubrication orifices are closed with bolt-on steel plates. First usage of the drilled block was on May 2, 1998, effective with engine serial number 6R408505.