If your machine does embroidery, change the needle at least every 8 hrs. However, I usually flex because if the design is dense and lots of stitches like 40,000 (anitagoodesigns are good for that) I change it sooner. I can' purchase a needle for $1.00 easier than have a design messed up when nearly finished. With my computer machines they need to be professionally cleaned annually. I do the best I can with the bobbin area every time I change the bobbin, but the lubercation isn't oil so I was told by a dealer............my older mechanical machines.......no problem do it myself. calla