That all having been said, the basic painting or phosphating, E-Coat, etc. on Mazda subframes and suspension members is really, really poor. And further, my sense (based on what I have seen on this Forum) - is that just like Toyota Tacoma (Rockwell / Dana Corp) frames, probably made who knows where, the steel that is sourced for those frames and suspension members appears to REALLY have a propensity to rust. These subframes and suspension members bear close checking, and if at all possible, pre-emptive additional paint and rustproofing if a person is so-inclined. You should not have to do this, though!