Oui et Non! Yes you can go then, but NON, it will not be direct-you overlook the changes to do then. The (mostly only 1 couchette) car direct only runs in main summer season and to same times-it gets shunted from train 1 to 2 to 3 in the time you now do the change yourself.

The Swiss claim to have ´the slowest express´ in EUR but this train may also well confirm to that.

Thanks for the replay @mcadv

In this case, do you still recommand to travel from Bucarest to Istanbul in may ? or it will be really exhausting ?

What are the changes to do between Bucarest & Istanbul ?

Any other easier plan ?

We have 15 days interrail pass and we want to do :

Paris => Wien => Budapest => Bucarest => Istanbul (stay for 4 days) => Bucarest => Budapest => Paris

Bulgarian Rail and turkish rail are always silent with the start date of the direct carriage :) 

The current timetable looks quite good and it let me assume that the direct carriage will operate from 26th March till October but there is no gurantee The changes are listed in the timetable on the website of BDZ but i prefer to have an extra stop in Sofia and travel then from Sofia directly to Istanbul