I've had some for about a year.....never thought it did much --until yesterday! I have 2 half cones of thread for my longarm. I was doing freemotion on a charity quilt. Tried to use one for the bobbin thread but it kept breaking. I finally used the 2nd cone and set the 1st one aside. Then, down to the last 6 inches I needed another bobbin!!! Was lazy, didn't want to unthread my machine, so I put some of the lubricant on the 1st cone, waited a minute, then started winding. WOW it worked SO well!!!! No more breaking!!!!
BTW - I talked to the repairman/technician/owner of the shop about it when he set up my machine. He's worked on all types of machines and said it absolutely will not hurt your machine. My DH said it's a silicone lubricant and I know he uses the "mechanic version" all over -- with cars and motorhome.