Well to put it in some kind of perspective, the oil capacity of the sump on something that big will be around 25 litres of oil. The engine sat on the floor on it's sump will be about 4foot tall and about 3 foot long. The Flywheel will be about 600mm in diameter. Piston and rod combination will be roughly 300mm long and pistons about 5 to 6 inch diameter. The crank pulley will be about 300mm in diameter.

This is all generalisation and not exact but educated guesses from past experience of working on HGVs.