My DH, the sewing machine technician, says that if the oil is the least bit yellow, it is bad and needs to be thrown away. If you use it in that state, it will get gummy inside of your sewing machine and then you will need to take your machine to someone like my DH! :shock:

More info I didn't know. I love this board.

I think its someting to do with the metal can..because it said in plastic it lasts forever.

Remember when all the cans for gas were metal, now plastic. :D

Oil can go bad in a plastic bottle too. I've seen it happen! It is the light and oxygen that make it go bad. The best thing to do is check and see if there is any color to the oil--if there is, then throw it away--don't use it on your machine--because if you do, it will eventually gum it up and cause problems!