Rust protection in 2025.

[3hands]

I’m about to spend the weekend de-rusting the chassis, and am looking for a wax product to apply to the raw steel. Wax is my first option, as it stays tacky and I’m wondering who’s used what. I’m also incredibly open to other products that aren’t wax based. My e28 will not be subjected to the harsh Canadian winter, but I want the best protection possible. 

thanks so much in advance,

Alex 

[stuartinmn]

I've heard a lot of good things about Krown rust control.  They sell products so you can do it yourself, or you can go to one of their shops to get it applied.  https://www.krown.com/en/
There are plenty of home remediesm one I know of is to use chainsaw bar oil followed by a drive on a dusty road.  The bar oil is sticky so it holds on to the chassis, and a layer of dust helps seal it in.
Both methods are going to be messy, of course, so your undercarriage won't pass muster at the next concours.  

edited to add:  If you aren't driving your car in the winter, then adding extra rust protection isn't as necessary - keeping the car clean is the best thing, along with avoiding driving in the rain if you can (and making sure to dry up any water that collects in rain gutters, etc.)  In the spring, don't take the car out on the first nice day, wait a while for the road salt to wash away first.

[DavidE9]

POR-15 is popular with the E9 guys. 

[DavidE9]

I just looked at that Krown site. The video shows them spraying it pretty much everywhere without much prep. I've never heard of that actually.

[Chicagotrader92]

I have Rustoleum rust-resistant sound-deadening paint on my inner wheel wells and Eastwood corrosion-resistant chassis paint on some of the underside suspension components. However, I also do not drive my car in the snow and wait until the roads are dry... The "Salts Gone" cleaner seems worthy to keep on hand as well. Neutralizing / getting the salt off fast is arguably just as important as protecting against it. 

[thhaar]

I've used Fluid Film with great success for many years here in Connecticut, where roads are salted with abandon every winter even if there's little snow or ice these days.  My mechanic now swears by it also and recommends it to his customers.  The easiest way to apply it is via spray cans, not the big kit with spray apparatus they sell.  
 

[3hands]

Thank you so much everyone!

the wax seems to be prohibitively expensive for doing essentially the same job as the much less expensive products. 

I’ve got a ton of research to do this evening! 

alex

[Mashford]

Hey Folks,

In the spirit of "Rust protection in 2025", I have rust patches at the four jack stand points, some worse than others.  Here are photos from two of the four:

 





 

When I got the car back in 1997, I put jack stands at these points thinking I was doing it correctly, and they punched through the sheet metal of the body part along each side.  I am not sure what that body panel is called: runner panel?  One point of each v-shape of the jack stands just went up into the metal when I lowered the car.  I never understood precisely how I was supposed to set the stands without doing damage to the sheet metal.  Anyway, I have rubber pads now on my jack stands.  Also, I have been putting stands under the front frame since this first happened, to avoid it getting worse. 

Now I see it is getting worse (growing) and I want to nip it in the bud.

Any suggestions / links to other posts / links to videos anyone could make?  Do I grind, then sand, then fill with bondo (putty), sand some more, paint?  I am not a body resto person, so hoping this isn't too much to handle in my driveway.

My biggest is that it has spread into places where I can't get to it to stop it.  

I do have a bottle of Skyco's "OSPHO" rust treatment at hand.

Thanks for any advice!!

[stuartinmn]

Unfortunately the only long term cure is to cut out the rusted sections and weld in new metal (and if you remove the paint and undercoating, you'll undoubtedly find the holes are a lot bigger than they look now - think about how icebergs only show 10% of their size above water.)  The holes could be filled in with fiberglass, but eventually the metal will continue to rust until the fiberglass patch falls out.  Using body filler only is the sort of thing 'buy here, no credit necessary' used car lots will do when flipping cars.

[Mashford]

Unfortunately the only long term cure is to cut out the rusted sections and weld in new metal (and if you remove the paint and undercoating, you'll undoubtedly find the holes are a lot bigger than they look now - think about how icebergs only show 10% of their size above water.)  The holes could be filled in with fiberglass, but eventually the metal will continue to rust until the fiberglass patch falls out.  Using body filler only is the sort of thing 'buy here, no credit necessary' used car lots will do when flipping cars.

Got it. Thanks. I guess I will contact a body shop. 

[Foonfer]

So nice to see someone motivated and dedicated to saving their E28.  Kudos to that.

Seems a bit weird that your car shows what appears to be substantial, terminal rust-through conditions, and at the same time they seem to be very localized.  Perhaps it's the way you kept the car stored, but I would also look into the usual places:  The rear bumper mounts, the battery tray, the floor panels, around the trunk floor, at the seam between the front quarter panels and the car body, at the corners of the front windshield, at the perimeter of the sunroof...  and yes, you will need to replace metal.  Lots of sanding, lots of cutting, lots of cleaning, and then sanding more, then cutting, bending, measuring, welding, etc.   There are many videos on Youtube showing great work.  It is very, very labor-intensive.  When sanding, cutting and welding, be very careful with "what's behind" - you might find yourself having burned through electrical wiring, hoses or other important stuff that doesn't want to be tampered with.

Not sure if anyone has had experience with "dry ice blasting" to clean up in preparation for coating application - please chime in.

Best of luck, we'll be cheering from the sidelines!

[Mashford]

So nice to see someone motivated and dedicated to saving their E28.  Kudos to that.

Seems a bit weird that your car shows what appears to be substantial, terminal rust-through conditions, and at the same time they seem to be very localized.  Perhaps it's the way you kept the car stored, but I would also look into the usual places:  The rear bumper mounts, the battery tray, the floor panels, around the trunk floor, at the seam between the front quarter panels and the car body, at the corners of the front windshield, at the perimeter of the sunroof...  and yes, you will need to replace metal.  Lots of sanding, lots of cutting, lots of cleaning, and then sanding more, then cutting, bending, measuring, welding, etc.   There are many videos on Youtube showing great work.  It is very, very labor-intensive.  When sanding, cutting and welding, be very careful with "what's behind" - you might find yourself having burned through electrical wiring, hoses or other important stuff that doesn't want to be tampered with.

Not sure if anyone has had experience with "dry ice blasting" to clean up in preparation for coating application - please chime in.

Best of luck, we'll be cheering from the sidelines!

Thanks! No other significant rust elsewhere on the car. I had quite a bit repaired after a low speed re-ender got me enough insurance to cover 70% of what needed to be done and pitched in the rest (rear pneumatic / mounts, front quarter panels, hood).     I swear these are from bad setting of Jack stands years ago when I couldn’t for the life of me figure out how to avoid crushing soft sheet metal. 

[stuartinmn]

If there's a bright spot, those rust through spots are in locations that aren't very visible.  Replacement metal patches don't need to be perfectly welded and metal finished, so if they're a little lumpy and bumpy it won't really matter.

[Mashford]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I took it too a body and restoration shop recommended by a trusted mechanic.  I had rust behind right front wheel, too, in the wheel well. Pictures are not in order, but you get the idea. They also patched and coated some scary dents I put in the front subframe rails, again with bad placement of jack stands in the past.   I think they did a great job!  Now I feel better about taking on rear subframe bushings and a bunch of bad joints in the front end... 20 years since I did any of that, and a bit of a project to take on in the driveway... but I am thinking it through.

I am going to be MUCH MORE CAREFUL with jack stands and fix and gaps in wheel well plastic protectors, monitor closely, etc.

 


 


 


 

[3hands]

Thank you for all this! 

Alex 

[vinceg101]

I went through this on my M535i. Both lower rocker panels at the jack points were damaged and rusted out as well as both front lower rear wheel wells at the floor boards. There was evidence that there may have been similar rust damage at the rear subframe bushing mounts but they were modified when the new suspension was put in 2 owners before me. (The car started its US life in New Hampshire and Maine, it wasn't there long but long enough for road salts to do a number).

I documented the repairs it here on pages 5 & 6 forums.mye28.com/viewtopic.php?t=139465&start=150