A gas turbine engine, comprising: a fan section; a compressor section comprising a low pressure compressor and a high pressure compressor; a combustor in fluid communication with said compressor section; a turbine section in fluid communication with said combustor, the turbine section comprising a low pressure turbine and a high pressure turbine; an outer shaft that interconnects the high pressure compressor and the high pressure turbine; a low speed spool including an inner shaft that interconnects the fan section, the low pressure compressor and the low pressure turbine; a plurality of bearing structures that support said inner shaft and said outer shaft, wherein a first one of said bearing structures includes a bearing compartment; a buffer system (60; 160; 260) that selectively communicates a buffer supply air (62; 162; 262A, 262B) to pressurize said bearing compartment, wherein a low pressure bleed air supply (64; 164; 264A, 264B) is communicated to said bearing compartment in response to a high power condition of the gas turbine engine and a high pressure bleed supply air (66; 166; 266A, 266B) is communicated to said bearing compartment in response to a low power condition of the gas turbine engine, wherein said buffer system (60; 160; 260) includes a valve (68; 268A, 268B) that selectively modulates between said low pressure bleed air supply (64; 164; 264A, 264B) and said high pressure bleed air supply (66; 166; 266A, 266B); the gas turbine engine further comprises a controller (70; 170; 270) that selectively modulates said valve (68; 268A, 268B) in response to a power condition; and in that the fan section is driven by a geared architecture at a lower speed than the low speed spool, wherein the first bearing structure is forward of the geared architecture, and the plurality of bearing structures further comprises a bearing structure aft of the geared architecture. a fan section; a compressor section comprising a low pressure compressor and a high pressure compressor; a combustor in fluid communication with said compressor section; a turbine section in fluid communication with said combustor, the turbine section comprising a low pressure turbine and a high pressure turbine; an outer shaft that interconnects the high pressure compressor and the high pressure turbine; a low speed spool including an inner shaft that interconnects the fan section, the low pressure compressor and the low pressure turbine; a plurality of bearing structures that support said inner shaft and said outer shaft, wherein a first one of said bearing structures includes a bearing compartment; a buffer system (60; 160; 260) that selectively communicates a buffer supply air (62; 162; 262A, 262B) to pressurize said bearing compartment, wherein a low pressure bleed air supply (64; 164; 264A, 264B) is communicated to said bearing compartment in response to a high power condition of the gas turbine engine and a high pressure bleed supply air (66; 166; 266A, 266B) is communicated to said bearing compartment in response to a low power condition of the gas turbine engine, wherein said buffer system (60; 160; 260) includes a valve (68; 268A, 268B) that selectively modulates between said low pressure bleed air supply (64; 164; 264A, 264B) and said high pressure bleed air supply (66; 166; 266A, 266B); the gas turbine engine further comprises a controller (70; 170; 270) that selectively modulates said valve (68; 268A, 268B) in response to a power condition; and in that the fan section is driven by a geared architecture at a lower speed than the low speed spool, wherein the first bearing structure is forward of the geared architecture, and the plurality of bearing structures further comprises a bearing structure aft of the geared architecture.