Engines - Oil System (PW4060) 
- Company Limitations - Engine Oil Quantity
- Boeing - Flight Crew Considerations for Engine In-Flight Shutdown
The oil system provides pressurized oil to lubricate and cool the engine main bearings, gears and accessory drives. The oil system also provides automatic fuel heating for fuel system icing protection.
As an engine is started, a quantity of oil will transfer from the oil reservoir to the engine bearing compartments and gearbox. This results in a decrease of indicated oil quantity. During engine shutdown, the indicated oil quantity increases as the oil is returned to the reservoir. In addition, oil temperature will tend to vary with engine RPM such that, as RPM is increased, temperature increases. As RPM is decreased, temperature decreases.
primary Oil Pump
The oil system is pressurized by a primary (engine-driven) Oil Pump (driven by the N2 rotor via the accessory gearbox).
Oil Filter
From the pump, the oil flows through the oil filter where contaminants are removed. Should the oil filter become saturated with contaminants, oil will automatically bypass the filter. The EICAS advisory message L/R OIL FILTER displays indicating the oil filter is bypassed.
Oil Coolers
The oil flows through the oil coolers where fuel and air are used as the heat sink, and is then delivered to the engine main bearings, gears, and accessory drives.
Scavenge Pump
The oil is then returned to the reservoir by a scavenge pump (also driven by the N2 rotor).
Oil pressure, temperature and quantity are displayed on the secondary engine display.
Oil Pressure is measured prior to entering the engine (downstream of the pump). The L/R ENG OIL PRESS light illuminates and the L/R ENG OIL PRESS EICAS advisory message displays to indicate oil pressure is low.
When the oil pressure is at or below the minimum limit, the EICAS indication changes to red.
Oil Temperature is measured after leaving the engine, prior to entering the reservoir. When the oil temperature is in the caution range, the EICAS indication changes to amber.
There is no minimum oil quantity limit (no amber or red line limit). There are no operating limitations for the engine oil quantity and there are no flight crew procedures based solely on a response to low oil quantity.