Question:
When singing emiros on shabbos do we say Hashem's name or do we say "Hashem"?
Answer:
When we are praising Hashem, such as when singing zemiros, we are allowed to say Hashem's name. We just should be careful though not to interupt in the middle, or repeat words, so that the sentence with Hashem's name is said clearly.
Best wishes
Sources:
Chayei Adam 5-27, KItzur Shulchan Aruch 6-3, Halichos Shlomo 1 Chap. 22 ftnt. 29, Kodesh L'Hashem 8-1.