Ive tried them all! ( btw,I always open my filter after every oil change and check for deposits,I'm anal like that) , I use only OEM now.

 

I've never opened a filter to look at its contents, but may consider it. Unfortunately, I don't know what I would be looking for.
What differences would I see between a 3,000 miles oil change and a 15,000 oil change?

 

A used Oil Analysis is what you get if you want to know what's up with your engine. Opening the filter can only really tell you if you are about to need a new block to screw the next filter onto. A more-used filter will look nastier than a less-used one. Without proper analysis equipment, however, seeing disturbing chunks in your filter is almost as useful as an Airbag light after your bag deploys in a crash.

But it's good clean ( ? ) fun anyway.