|This is an off the cuff sort of tip for those who get excited by the unconventional or finding new uses for everyday things.
I've heard of silicone thread lubricant before but usually it's in relation to keeping inexpensive thread on embroidery machines from breaking.
I found some amazingly heavy duty #16 thread. Usually they sell #20 as "jeans thread" the #16 is like sewing with thick fuzzy rope. It pushes the limit of a 18/110 jeans needle. I've considered a 19/120 topstitch needle but haven't gotten around to ordering them yet. I use this thread in the bobbin and needle with tension set at the maximum for very tight stitches. There is no way this thread is going to break but it does create a lot of friction on the machine guides and needle eye.
Heavy Duty Silicone -Multi-use Lubricant
It's not found in the sewing section, look in hardware or automotive. This 11oz can costs a couple bucks and claims to, "Stops Sticking, Binding, Squeaking on Nylon, Rubber, Wood, Metal, & Non-Metal Surfaces". Well that sounds just about right to me! I did a test spray on some thread to be sure it wasn't going to be oily or change the thread color, neither happened. It leaves a very light essence of silicone on the thread, is orderless and doesn't come off on your fingers at all. After my test I saturated the entire spool and left it outside to dry. This spray does have a strong chemical smell until it drys so outside seems best.
It's great! My thread now runs smoother, the needle gets a slight bit of lubricant and my stitch quality has improved. If you used an ounce, which seems like a lot, it would only cost around 25 cents per application. This is far less then the brands marketed specifically to sewers and from what I can this spray is a much lighter weight silicone.
There are multiple brands, I think the key is to get one that is a "dry" silicone not the "wet" variety and of course test it yourself to be sure it's what you want.