Originally Posted by
Top of climb
A better question might be - will CX check in even be open when you depart for Oslo? Keeping in mind CX is in T3 and your conformance cut off time to be airside at T5.
CX is not operating the check in for the initial LHR-OSL or OSL-LHR.
If OP wants to bring baggage to HKG and does not want the luggage to fly to OSL and back, OP will have to keep the luggage in T3 landside storage while on the OSL turn, go landside (re-enter UK) in T5 after OSL-LHR (I hope OP has a e-Gate readable passport for this...), travel T5-T3 landside and check it in with CX (he should be allowed to check in additional pieces during "transit"?).