The name of the tube is the "bowden tube".  Or just "the bowden".   OH!! Fiberflex 40D!!!  Oh I saw that but wasn't familiar.  That is similar to "Ninjaflex".  I think that is also 40D.  maybe?   Okay so Ultimaker has is a bowden printer and has more trouble with filaments that are so flexible.  But you can do it.  So yes absolutely put oil on the filament (to get into the bowden).  Here are some steps you need to do:   1) Print maybe 10C hotter than they recommend