Piston Slap: In God We Rust, Part III

TTAC commentator Kovalove writes:

Hi Sajeev,

Long-time lurker on a daily basis for over 5 years now. Not sure if this is a worthy question for Piston Slap but here we go: In about two weeks’ time I’ll make my final payment (0% loan ftw) on my 2008 Mazda3 GT 4-door (‘S Grand Touring’ in US spec) with just over 97,000 km. It has served me well with no at-cost repairs other than routine maintenance (some minor stuff was covered by warranty). I have been looking forward to payment-free living and would happily keep the car for many more years, but one thing has been rattling around in the back of my mind…

I live up in the Great White North in the Toronto area where road salt is used from November through to the end of March. After winter 2012 I noticed some early signs of rusting on the inner lip of the rear wheel openings. I was annoyed but not really surprised as this is a well documented phenomenon with Mazdas. I regularly see ‘3s a couple of years older than mine that are rusting badly in numerous areas on the sides and rear end.

Supposedly the 3’s resistance to rusting was improved with the refresh in 2007, but only time will tell for sure. My question is whether there is any financial sense in getting rid of the car now before the rust gets serious, especially given the inflated used car market? For what it’s worth, I will be debt-free with the repayment of this loan. Presumably a badly rusted car would plummet in value despite being otherwise mechanically sound? According to many reports, repairing the rust on these cars is a mostly futile exercise and it comes back quickly. Thanks in advance!

Sajeev answers:

Ah yes, we are revisiting the rusty Mazda problem for the third time in this series. Too bad the 3’s mild redesign didn’t/couldn’t address this problem, and it appears Mazda Canada’s warranty doesn’t cover rust damage. Did I misread that part with the exclusions?

“Damage or surface corrosion from the environment such as: Acid rain, airborne fallout (chemicals, tree sap, etc.), salt, road hazards, hail, wind storm, lightning, floods and other natural disasters.”

Don’t take my word for it, read your owner’s manual (RFTM) and verify.

Now someone can quickly repair the rust if it’s small/localized ( DIY is not impossible, either) and buy more time before the Rust Lord takes over. But will it buy enough to justify ownership to you? And it is worth it to your pocketbook if you can sell it for a price that makes you happy and gets you into a newer car that’ll make you happier?

Now that’s the real question, me thinks. So what is your threshold for pain? Without supporting photos or a comprehensive underbody inspection, who knows how much pain you got coming?

Take it from the idiot restoring his “rust free” 1983 Lincoln Continental Valentino: once you tear into a rust repair project, you’ll find more of it. Peep the photo below: I thought my Valentino’s decades old, well-known rust hole under the battery was just that! But oh noooo, the rust seeped down farther, down to the base of the radiator support.

Now is mentioning my Valentino in the same blog post as your Mazda 3 a fair comparo? Absolutely not!

We all assume that the “young” Mazda won’t be this sinister: at least we assume this. But you know about them people who assume too much!

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.