Good to know. I have no idea if 3-in-1 was ever used in the old machines I have...if Dad had a choice, I'm sure that's what he used. I have never used it in any of my machines and of course 3 of mine don't use oil at all, but the FW and the treadle do...I'm gonna bet that they both have had 3-in-1 in them at some time in their life!
This is why you need to take your old machines in to be serviced so they can be cleaned out of all that "gunk".
Thanks