A method of indicating oil quantity in a lubrication system of an auxiliary power unit, the lubrication system having a lubricating oil and a pump to deliver the lubricating oil to a turbine, the method comprising: determining, via a controller, a raw oil quantity value indicative of a quantity of oil disposed within a sump of the lubrication system; establishing, via the controller, a gulp oil value, including establishing a startup gulp (42 ST) value during a startup phase of the APU, a latched gulp value (42 L) during an operating phase of the APU during a period when the APU is running, and a shutdown gulp value (42 SD) during a shutdown phase of the APU; determining, via the controller, an indicated oil quantity by adding the raw oil quantity value and the gulp oil value; depicting, via the controller, the indicated oil quantity on a display; and storing the indicated oil quantity when the APU transitions from the operating phase to the shutdown phase, wherein: the startup gulp value (42 ST), at initial startup of the APU, is equal to the indicated oil quantity that was stored at a previous transition of the APU from the operating phase to the shutdown phase, the startup gulp value (42 ST), after initial startup and until the APU has reached governed operational speed and transitions to the operating phase, is periodically determined as equal to a difference between a last indicated oil quantity value and the raw oil quantity value; the latched gulp value (42 L) is a constant value throughout the operating phase of the APU, and is equal to the startup gulp value (42 ST) that was established when the APU transitioned from the startup phase to the operating phase, and the shutdown gulp value (42 SD) is determined when the APU transitions from the operating phase to the shutdown phase and continues until the APU goes from governed speed to off, and is equal to the difference between the indicated oil quantity that is stored when the APU transitions from the operating phase to the shutdown phase and the raw oil quantity. determining, via a controller, a raw oil quantity value indicative of a quantity of oil disposed within a sump of the lubrication system; establishing, via the controller, a gulp oil value, including establishing a startup gulp (42 ST) value during a startup phase of the APU, a latched gulp value (42 L) during an operating phase of the APU during a period when the APU is running, and a shutdown gulp value (42 SD) during a shutdown phase of the APU; determining, via the controller, an indicated oil quantity by adding the raw oil quantity value and the gulp oil value; depicting, via the controller, the indicated oil quantity on a display; and storing the indicated oil quantity when the APU transitions from the operating phase to the shutdown phase, wherein: the startup gulp value (42 ST), at initial startup of the APU, is equal to the indicated oil quantity that was stored at a previous transition of the APU from the operating phase to the shutdown phase, the startup gulp value (42 ST), after initial startup and until the APU has reached governed operational speed and transitions to the operating phase, is periodically determined as equal to a difference between a last indicated oil quantity value and the raw oil quantity value; the latched gulp value (42 L) is a constant value throughout the operating phase of the APU, and is equal to the startup gulp value (42 ST) that was established when the APU transitioned from the startup phase to the operating phase, and the shutdown gulp value (42 SD) is determined when the APU transitions from the operating phase to the shutdown phase and continues until the APU goes from governed speed to off, and is equal to the difference between the indicated oil quantity that is stored when the APU transitions from the operating phase to the shutdown phase and the raw oil quantity. the startup gulp value (42 ST), at initial startup of the APU, is equal to the indicated oil quantity that was stored at a previous transition of the APU from the operating phase to the shutdown phase, the startup gulp value (42 ST), after initial startup and until the APU has reached governed operational speed and transitions to the operating phase, is periodically determined as equal to a difference between a last indicated oil quantity value and the raw oil quantity value; the latched gulp value (42 L) is a constant value throughout the operating phase of the APU, and is equal to the startup gulp value (42 ST) that was established when the APU transitioned from the startup phase to the operating phase, and the shutdown gulp value (42 SD) is determined when the APU transitions from the operating phase to the shutdown phase and continues until the APU goes from governed speed to off, and is equal to the difference between the indicated oil quantity that is stored when the APU transitions from the operating phase to the shutdown phase and the raw oil quantity.