An Interesting Find During An Oil Change

[HeyMoe!]

I took my '25 GT PP for a break-in oil change today (1100 miles). At 72 YO, I no longer crawl under cars, so I went to my dealer for this. As I was waiting, the Service Advisor and the tech guy sought me out in the waiting area.

They informed me that they had found some road salt under that infamous shield under the oil pan. Though I do not plan to drive this car in winter weather, the car showed up at the dealer early (January). I drove it home on a cold, but dry day, and put it into my garage until March. I imagine that there was some dry salt residue on the roads during the 40-mile drive home.

Back to the story--they asked me if I would be willing to take it to a car wash, without the shield in place, and do an undercarriage spray (the dealer does not have a car wash tunnel). They mentioned that another GT owner had the same issue, and was not aware. They ended up having to do a major subframe replacement on his car.

I did the wash, brought it back to the dealer, and they put the shield back in place before I drove home. I was happy that they noticed this.

I will not be driving this car during winter. Though, I know that some of you will do so. Not to be an alarmist, but perhaps it is something for those of you who 12-month your GT in northern areas to keep on the radar.

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[Will2]

Thanks for the tip. Kind of scary someone already had serious subframe deterioration on a new model car, even if it was exposed to some salt/water. I thought American cars were known to be stronger against rust, whereas Japanese cars rusted more easily.

 

[GrabThatBlue]

It's crazy that these Mustangs are like cardboards. I've heard that's because of the cheap American steel.

I drive my 25.000 USD Volkswagen for 14 years, through harsh winter with salt every single day.
Have 250.000 miles on the dash, outside parking, no undercarirage treatment from my side and the car is running fine with little to no rust.

And these brand new Mustangs? Built this year, had 1 salt grain on the car and the car starts to rust.

 

[DarkkMatter]

Thanks for posting about this. I'm going to make a note of it to the service people when I get mine changed during winter time or after a storm.

I only take it into brushless car washes and always try to get undercarraige wash as part of the car wash option.

 

[Terminus]

I'm only driving my 25 GT during the 5 month no snow/ice period on the calander (5/1 thru 9/30) here at 61° lattitude in the Great Land. The sheet metal does seem mighty flimsy.

I still have a fox body with 140k miles I drive some in the winter with snow tires & studs. The 86 GT has no significant rust. Just a little surface oxidation. It was built in Canada.

Interestingly I had an 86 F250 that I bought new that rusted out after 15 or 16 years.

I currently also run a 2004 F250 in the winter that also has 140k on it & little rust.

 

[Gregs24]

Thanks for the tip. Kind of scary someone already had serious subframe deterioration on a new model car, even if it was exposed to some salt/water. I thought American cars were known to be stronger against rust, whereas Japanese cars rusted more easily.

He didn't actually say that - it would most likely be an older S550 GT?

There is no way a subframe would rot out on any car in 2 years unless it was parked in the sea!

If the floorpan wasn't there it would still get salt spray on it.

Cars don't rust now because the steel is galvanised (bodywork) compared to the old days.

 

[MAT1955]

@HeyMoe! ..... Thank you for taking the time to share your experience with us. There are several interesting discussion points. The new "salting" of roads should be called "brining" of roads. The liquid brine they now spray stays on the roads (and subframes) longer. The "old" salt crystals were easy to get off with the water underspray at car washes. The "new" brine gets everywhere under the frame - every nook and cranny. Even driving on a dry road in the winter clouds of this $hit go everywhere. The new belly pan covers are worse than the old "open frame" configurations as the belly pans hold the brine/water/ dirt poultices against the frame longer in a wet format that can't dry-out easily. Worse yet, these areas are almost impossible for a car wash underspray to get at. Modern engines that run much hotter and dual catalytic converters cook these poultices, really speeding-up rust damage. What to do? For the vehicles we drive daily in the winter I have used clear oil undersprays on the undercarriages - NOT the waxy crap that actually traps moisture and causes worse damage than using nothing at all. I get the "winter" vehicles oiled every year (cost about $100) and do NOT use the car wash underspray option at car washes as that would just wash the protective oil off. This has resulted in no significant rust in vehicles that we kept 10+ years and the dealership mechanics bought from us for their children, family & friends. ......With my 2014 Mustang and 2024 Mustang ...... same clear oil treatment. The oil spray on the 2024 was done AFTER the belly pans were removed and @AZ_Ryan AFTER the patches from DIYvan.com were installed. Ha Ha ..... My 2024 Mustang will likely not ever be driven in the winter BUT if it was the oil treatment would protect it very well AND because it has belly pans that I believe promote rust even in the summer - the oil underspray will IMO 100% stop any rust there, again @AZ_Ryan for $100. :-) I'll try to attach a couple of pics. Just a clear free flowing oil that (like the friggin' brine road spray) gets everywhere. IF you have a Mustang that has already been subjected to road salt or worse yet road brine spray or even of you live in a coastal area - take it to a car wash and run it through the under spray several times. let it dry thoroughly and then have it under oiled. I use Corrosion Free oil spray now but in the past used a spray called Oil Shield. I have seen the same or very similar product from other manufacturers. Corrosion Free has a web site where you can but the product bin cans or even bulk with spray nozzle systems - for any of the DIY guys on the forum - especially the lucky ones with their own lifts.

 

[Ciulster]

When I dropped my plastic undertray to do my first oil change I got about 4 pounds of calcium chloride (which is basically road salt on steroids that my city has decided to use), dirt and rocks directly into my eyes. So yes if you have ever taken your Mustang for a drive on anything other than a beautiful sunny day you likely have a tiny bit of buildup of dirt and pebbles there.

As far as I could see I don't have any rust starting anywhere and the underbody quality/factory rustproofing seems to be very good quality in areas where it is exposed, though I'm still glad I got the dealer undercoat at time of purchase!

 

[roadpilot]

They mentioned that another GT owner had the same issue, and was not aware. They ended up having to do a major subframe replacement on his car.

A major subframe replacement on another 2025 GT due to road salt?

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