Where do you get an oil analysis done? How often should you have it done? what is the benefit?

Also, (hopefully this isn't going to start any arguements) what is a good oil filter to use? I purchased my truck used and don't know what filter is on it now.

Thanks guys, you are awesome!

http://store.avlube.com
http://www.lubricationspecialistllc.com/
http://www.blackstone-labs.com/

I've only done one UOA and bought from Avlube, I've done business with both AVlube and lubricationspecialistllc and both will do you right. Blackstone Labs seems to be a popular choice at bob is the oil guy.