Don't know about the liquid, but is it possible that you are threading your needle with the wrong end of the thread? Make sure you put the thread in the needle as it comes off the spool, not the cut end. Also, after I thread my needle, I smooth the thread between my fingers all the way to the end about 3 times BEFORE I put the knot in. It can also be that your thread is too long. Try using a shorter piece (12" or so)
My mom uses a bit of wax on her sewing thread.