ok shees a petrol motor and yes that is significent oil loss for a petrol motor but the milage is a little hight so there is engine wear . I would consider using a slighter heaver grade oil and here i reccoment you get advice from a proper mech of dealer becausse if you just up the oil grade willy nilly yoou can damage the turbo and you dont need this .so seek advise and try some different grade of mabey if you mech agrees some wynnes oil enhancer on your next oil change with the additional advisce of your mechanic .or friendly oil expert P.s castrol have s site to advise on oil products .just google castrol and most oil additives companys like wynnes .s.t.p..millers etc have good websites you can google and visit.of all these are just to put off the big day for a probabal enging overhaul s