An oil storage and filtration system for an engine unit, the oil storage and filtration system comprising: an on/off valve that selectively receives supply air, wherein the on/off valve defines an operating phase when receiving the supply air and in an on position and a standby phase when in an off position or not receiving the supply air; a fill/drain valve that receives the supply air from the on/off valve during the operating phase, wherein during the operating phase the fill/drain valve defines a drain state and a fill state that respectively corresponds to emptying and filling of oil from and into the engine unit; a control valve that receives the supply air from the on/off valve during the operating phase; a pressure/vacuum valve in fluid communication with the control valve; a storage tank in fluid communication with the pressure/vacuum valve, the storage tank configured to store oil in three conditions, the three conditions including a pressurized condition during the fill state, a vacuum condition during the drain state, and an atmospheric condition during the standby phase; a vacuum generator in selective fluid communication with the control valve, wherein the vacuum generator is in fluid communication with the storage tank during the drain state and fluidly isolated from the storage tank during the fill state; and characterized in that the system comprises a safety reservoir tank that is fluidly isolated from the oil, wherein the safety reservoir tank is fluidly connected to the control valve and receives the supply air from the on/off valve during the operating phase. an on/off valve that selectively receives supply air, wherein the on/off valve defines an operating phase when receiving the supply air and in an on position and a standby phase when in an off position or not receiving the supply air; a fill/drain valve that receives the supply air from the on/off valve during the operating phase, wherein during the operating phase the fill/drain valve defines a drain state and a fill state that respectively corresponds to emptying and filling of oil from and into the engine unit; a control valve that receives the supply air from the on/off valve during the operating phase; a pressure/vacuum valve in fluid communication with the control valve; a storage tank in fluid communication with the pressure/vacuum valve, the storage tank configured to store oil in three conditions, the three conditions including a pressurized condition during the fill state, a vacuum condition during the drain state, and an atmospheric condition during the standby phase; a pressurized condition during the fill state, a vacuum condition during the drain state, and an atmospheric condition during the standby phase; a vacuum generator in selective fluid communication with the control valve, wherein the vacuum generator is in fluid communication with the storage tank during the drain state and fluidly isolated from the storage tank during the fill state; and characterized in that the system comprises a safety reservoir tank that is fluidly isolated from the oil, wherein the safety reservoir tank is fluidly connected to the control valve and receives the supply air from the on/off valve during the operating phase.