I use Superior Threads titanium 80/12. It's been on my machine since October 2009 and sewing fine still
Bob Purcell says they last 8 times longer that other needles

I tend to put in a new needle when I start a new quilt. I say tend because I sometimes forget. My Bernina has a display when it is time to oil her or bring her in for a maintainence. So far I have only had to oil her and I have a back-up for when she needs to go to the shop. Since I CAN'T be without my machine, I try to clean out the lint after a big sewing job, check the thread route for lint and change the needle if needed.

Thanks everyone! I sew appreciate everyone!!!

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