A turbine engine strut stage extends through gaspath upstream of a guide vane stage. A carbon seal system seals a bearing compartment and has: a carbon seal mounted to the case and a seal runner on the spool; and a seal carrier carrying the carbon seal. The engine passes buffer air along a buffer air supply path internally through one or more first struts of the stage of struts. The engine drains oil along an oil drain path internally through one or more second struts of the stage of struts.