I helped a friend change the oil in his 2004 Mazda6 equipped with the
2.3 liter four cylinder engine a few days ago. I took pictures of the
process and created a quick guide.
The process should be the same for all 2003 to 2008 Mazda6 sedans.
Here's the gallery -
http://www.paulstravelpictures.com/Mazda-Mazda6-I4-Engine-Oil-Change-Guide
I hope someone finds it to be useful.
Cheers,
Paul Michaels
Ft. Lauderdale, FL