Allan line 1910 from Norway

I found my grandfather on a pass. list. He left Trondheim, in Norway, 7. september 1910. Name of the ship is Oslo. His goal was Nilson BC. He went to visit family and went back to Norway afther four years. I tried to find out more information, because I want to find my family there. How can I find out more information about his trip? The ship went from Trondheim to where??? His name was: Eilif Sundt Johansen Grøva, born in 1888. Vefsn/Vefsen, Nothern-Norway :-))