[Boostedphil698]

Hi everyone,

I have recently started looking into having rust proofing done my 435i, albeit it never sees salt or winter roads here in PA. The reason for this is, just recently my 13 year old honda which I've spent countless hours maintaining has developed rust in the pinch welds in the rear wheel wells. I thought I cleaned my car enough to stop corrosion but I didn't. I know about BMW's 12 year rust warranty and I know most rust proofing is a scam but as someone who keeps their cars well past 10 years, what are some thoughts? This stuff never crossed my mind until now.

[Billfitz]

Probably a waste of money. Japanese cars had a major problem with rusting out until a few years ago. I guess they don't use salt on their roads. The Germans do. However, while the body panels are anti-rust treated most of the suspension parts aren't. I always have a spray can of undercoating on hand when I'm under the car for an oil change or pull the wheels to rotate the tires. If I see anything starting to rust I spritz it.

[Boostedphil698]

Originally Posted by Billfitz

Probably a waste of money. Japanese cars had a major problem with rusting out until a few years ago. I guess they don't use salt on their roads. The Germans do. However, while the body panels are anti-rust treated most of the suspension parts aren't. I always have a spray can of undercoating on hand when I'm under the car for an oil change or pull the wheels to rotate the tires. If I see anything starting to rust I spritz it.

Most Japanese car manufacturers only warranty against rust for 5 years after that only time will tell how long till the pinch welds fail. I have noticed BMWs tend to have no rust but it got me thinking. My Civic's exterior is flawless, its when you look underneath it's a different story.

[Techno 9000]

I had the underbody and suspension of my 435 coated with Dinitrol when it was three years old. I've followed this up with some Bilt Hamber products at six years old. When it was up on a ramp at seven and a half years old and 52k miles the suspension components and fixings look pretty much as new.

In comparison my wife's car of a similar age and mileage that we've recently bought has similar components that are bubbling with surface rust under the black paint and fixings have surface rust.

So I think it's worth it. Total cost under £300 to date. I consider my car a keeper.

[Boostedphil698]

Originally Posted by Techno 9000

I had the underbody and suspension of my 435 coated with Dinitrol when it was three years old. I've followed this up with some Bilt Hamber products at six years old. When it was up on a ramp at seven and a half years old and 52k miles the suspension components and fixings look pretty much as new.

In comparison my wife's car of a similar age and mileage that we've recently bought has similar components that are bubbling with surface rust under the black paint and fixings have surface rust.

So I think it's worth it. Total cost under £300 to date. I consider my car a keeper.

Hmm maybe I'll consider this!

[toxik]

do I think modern BMWs need it, especially as compared to Japanese cars? No

would I pay for it if it was a big concern of mine? yeah, you're paying for a peace of mind not for rustproofing per se.

[Boostedphil698]

Originally Posted by toxik

do I think modern BMWs need it, especially as compared to Japanese cars? No

would I pay for it if it was a big concern of mine? yeah, you're paying for a peace of mind not for rustproofing per se.

I'll probably just skip it. I've read too many horror stories about undercoating doing more harm them good haha

[toxik]

Originally Posted by Boostedphil698

I'll probably just skip it. I've read too many horror stories about undercoating doing more harm them good haha

i'd agree with that 100%. my car has over 50k miles, daily driven in northeast through winter and salt, is over 5 years old and has no rust issues at all. the little bit of surface rust on some bolts isnt even that bad.

the only rust prevention i'd do, if i upgrade my suspension, i'll probably get coilover covers. there's something very satisfying about having shiny suspension with no rust on it.

[Boostedphil698]

Originally Posted by toxik

i'd agree with that 100%. my car has over 50k miles, daily driven in northeast through winter and salt, is over 5 years old and has no rust issues at all. the little bit of surface rust on some bolts isnt even that bad.

the only rust prevention i'd do, if i upgrade my suspension, i'll probably get coilover covers. there's something very satisfying about having shiny suspension with no rust on it.

That's always an option for protecting the suspension. I don't drive my car in the winter so I'm probably gonna forego worrying. Just sucks I have to look into getting a new daily soon. My civic is starting to rust enderneath.

[alohasurftoad]

DIY

B'laster Surface Shield. unlike rubberized undercoating, this is lanolin based and basically goes on as a waxy oily(but not runny) sheen. Less than 4 spray cans should be enough. to get at the underside, jack stands would work but a lift would obviously be better. I got mine from home depot.

https://blasterproducts.com/product/surface-shield/
https://blasterproducts.com/surface-shield-faqs/

.

[Moupe]

Another one to look into which I use for long term Mg wheel storage. I went with this after a fair amount of research back then. Apparently it was developed by the Boeing company for the aerospace industry:

https://boeshield.com/why-boeshield-2/

"Boeshield T-9® gives superior corrosion protection and waterproof lubrication in an easy-to-apply, long-lasting formula.
Unlike other products, Boeshield T-9® cleans, lubricates and protects. One high-performance formula does it all. Whatever the application, whatever the conditions, you can count on T-9 to work harder, last longer and perform better.
On a seafaring yacht, a dusty ATV or a shower door, T-9 has you covered. T-9 endures muddy bike trails, rain-soaked back roads and salted highways. It withstands farmer’s fields, offshore oil rigs and carpenter’s workshops. For everyone from firefighters and road crews to cyclists and sailors, Boeshield T-9® is the proven solution.


True aerospace technology. T-9 was developed and licensed by global aerospace leader, The Boeing Company, to fill a need for high-performance, long-term metal protection and lubrication. T-9’s unique formulation of solvent carrier and paraffin wax coating was engineered to penetrate crevices deeply, displace moisture, dissolve minor corrosion, and leave a clean, waxy coating with lasting durability—without using Teflon, silicone, fluorocarbons, MEK, or acetone."

[Boostedphil698]

Originally Posted by Moupe

Another one to look into which I use for long term Mg wheel storage. I went with this after a fair amount of research back then. Apparently it was developed by the Boeing company for the aerospace industry:

https://boeshield.com/why-boeshield-2/

"Boeshield T-9® gives superior corrosion protection and waterproof lubrication in an easy-to-apply, long-lasting formula.
Unlike other products, Boeshield T-9® cleans, lubricates and protects. One high-performance formula does it all. Whatever the application, whatever the conditions, you can count on T-9 to work harder, last longer and perform better.
On a seafaring yacht, a dusty ATV or a shower door, T-9 has you covered. T-9 endures muddy bike trails, rain-soaked back roads and salted highways. It withstands farmer’s fields, offshore oil rigs and carpenter’s workshops. For everyone from firefighters and road crews to cyclists and sailors, Boeshield T-9® is the proven solution.


True aerospace technology. T-9 was developed and licensed by global aerospace leader, The Boeing Company, to fill a need for high-performance, long-term metal protection and lubrication. T-9’s unique formulation of solvent carrier and paraffin wax coating was engineered to penetrate crevices deeply, displace moisture, dissolve minor corrosion, and leave a clean, waxy coating with lasting durability—without using Teflon, silicone, fluorocarbons, MEK, or acetone."

I probably wouldn't do the whole undercarriage. Just the areas of the pinch welds.

[Billfitz]

I'm not sure you can even reach them, the fender liners shield them.

[Boostedphil698]

Originally Posted by Billfitz

I'm not sure you can even reach them, the fender liners shield them.

That's true. BMW has done a good job at shielding them. Honda, not so much lol. But you have pinch welds that run down the bottom of the from rear wheel well to the front wheel well.

[freakystyly]

https://f30.bimmerpost.com/forums/sh...d.php?t=646007

Your car might be pretty close to this... not a lot of people look under there.

[Boostedphil698]

Originally Posted by freakystyly

https://f30.bimmerpost.com/forums/showthread.php?t=646007

Your car might be pretty close to this... not a lot of people look under there.

In that case I wouldn't do anything. I'm still learning these cars. I knew my Honda in and out.

[tturedraider]

Overall BMW’s factory rust inhibiting treatment is very good and gets in all of the nooks and crannies. Probably one of the biggest cons to aftermarket rustproofing is the likelihood that critical drain ports will end up getting clogged and create more problems than might be solved. Just fyi BMW’s rust warranty is a perforation warranty. It guarantees that rust will not perforate the sheet metal within twelve years.

[MidtownMike]

Originally Posted by tturedraider

Just fyi BMW’s rust warranty is a perforation warranty. It guarantees that rust will not perforate the sheet metal within twelve years.

So if you get a rusty spot better start poking it with a screwdriver.

[Boostedphil698]

Originally Posted by tturedraider

Overall BMW’s factory rust inhibiting treatment is very good and gets in all of the nooks and crannies. Probably one of the biggest cons to aftermarket rustproofing is the likelihood that critical drain ports will end up getting clogged and create more problems than might be solved. Just fyi BMW’s rust warranty is a perforation warranty. It guarantees that rust will not perforate the sheet metal within twelve years.

I saw that. I'm planning on keeping the car. Just trying to not go through what I'm going through with my Civic. I have to plan to buy a new car now haha.

[agentorange]

Now I remember why I moved from England to the desert SW.

[CJKaz]

2016 328ix, off lease. Brought it home and immediately pulled all of the under panels, windshield cowl and wheel well liners. Shot about 4 cans of fluid film (with flexible wand) in all locations, doors, quarter panels, unibody rails. Likely not needed, as they are well protected from the factory. Evident looking in those hidden areas. 5 years later, all is well.

[Musashi]

2014 335i XDrive, 175,000 Kms, 7-8 winters driven, Canada, 12% salinity. In winter 2015 i had an expert do it (no holes), he removed the skirt covers. He showed me how salts and debris, on older BMWs got sucked through small holes and got trapped. so if anything removing the panels to clean is essentials. never did it since, and exposed metal, around the corners, suffered, springs, sway bars etc. the Brake line had rotten and the cable and housing had to be replaced august 2024. This winter decided to do another exposed area coverage, but so many new components, suspension, springs new HRE, it is all clean. but the rustproofers found tiny perforation bubbles around the rear well where the quarter panel meets the plastic bumper cover! I was not just surprised, looked like paint spray etc, but more surprised when, home, found multiple forums on this issue and warranty swaps of the panels.

That area cannot get any rustproofing in - so rustproofing would have made no difference, unless drilling holes, but even then, unlikely. too much insulation in the rear well well so I have no idea how the salt and water sneaks in that rear area. Must be a low pressure spot that sucks in. So i will make the move for a 12 year perforation warranty, this must have started year 9.

And yes no comparison with my old Japanese, 2006, 235,000 kms, cheaper panels, thinner, less protected etc. but perforation rust is perforation rust so based on other F30 entries, BMW has a vulnerability there. Specifically it makes it that washing of any kind never dislodges the salt and i wonder if something happens when they dip it and it does not get the best galvanization or paint protection there, on the inside..