The 2.3l passenger side motor mount (aka right front or PMM) is a very common failure. The motor mount has a fluid filled center to dampen engine vibrations. Unfortunately they crack, fail, and ooze hydraulic fluid. Many with less then 50,000 miles of use.

I wanted to replace mine with a better mount, but didn't want to introduce any new unwanted vibrations. I searched for quite some time to find the best OEM replacement at a reasonable price. I found a unit that seems to be highly endorsed by those installing it, so I bit the bullet and was pleased with the results.

This article applies to the 2.3L engines powering the 2004-2009 Mazda3 and 2006-2009 Mazda5.

Pictures show a Mazda3, though a Mazda5 will be very similar