I have done several quilts with gold metallic thread and everytime I swear it will be the last! The last time I was doing a quilt at Christmas (7,000 ft. of gold metallic thread) about a quarter of the way through I was ready to pull my hair out. Hubby came to the rescue (again) and said, "there must be something that will let the thread flow smoothly." I told him I had seen a product called Sewer's Aid but didn't know what it was. So we looked it up on the internet and it's silicone!
So he went to his shop and got me a spray can of silicone...which will not hurt the thread or the fabric...and I sprayed the bobbin AND the thread spool! I used the biggest needle I had (18) and cotton thread in the bobbin, and WOOHOO it worked! I sprayed the bobbin heavily every time I changed it, as well as kept the thread spool sprayed, and I still had some breakage but not nearly as much as before nor as frustrating.
I have not used other colors of metallic thread, but I can't imagine it wouldn't work on them as well. I haven't confirmed it, but I understand that the quilter that won Best of Show at Houston this year, Sharon Schamber, uses silicone by the "bucket." Good Luck!