To Fix or Not to Fix? The Dilemma of Underbody Rust on a 6MT 2012 128i M Sport

[E82BSM128i]

Any opinions on what kind of work and cost to be expected to restore a beloved black/black BMW 128i, a rare gem with a 6-speed manual transmission and M Sport package, despite underbody rust and some light rusting beginning under the rear wheel wells as well as side skirts. The rear subframe also has rust but I have coated in Tremclad Rust Reformer paint for the time being.

I know this car is no collector's item - but a 6-speed manual transmission with M Sport package is a coveted combination.

[Lester]

It would depend on whether the rust is just surface. It could probably be sandblasted anc primed/painted by an auto body/restoration shop for 1-2$k.

[WrathOTM]

Pics?

[NorthernDancer]

Just pay $125 each Fall to get it rust proofed.
In 1978 I had to fix the window mechanism in my 1971 Ford. Car came from Alberta the year before, now I'm in Barrie. Saw minor rust on the inside door. Took a paint brush and clean engine oil and "painted" the inside of the door with oil. In 1985 while in Montreal I junked the car; car had 1 good door and 3 rusty ones.

[E82BSM128i]

Thanks for the replies. Here are some examples to show the kind of rust this 128i has. The wheel wells and a door panel with a rusting bubble surface was quoted for $1000 to fix. The cross brace (or whatever that piece is called that is closer to the mid section of the car) will not be fixed as per the shop since its not structural and the rear bumper is also surface rust according to them.

[bnace10]

Also depends on mileage, anything over 100k miles I wouldn't even bother. Sell it and buy a different one, it will be cheaper.

[tracer bullet]

Originally Posted by bnace10

Also depends on mileage

Agreed, along with interior condition.

And your willingness to DIY it vs. send it out, your money supply, your free time, etc. Oh, and if you want to flip it, have fun for a few years and move on, keep it a really long time?

[NorthernDancer]

Oh my that's far too much gone to spend any money on

[Olgeezer1]

Hate seeing this stuff. Not trying to kick you when you're down but there's only one way to prevent this in Canada and it's a winter beater. Mine was about the same price as a good set of winter wheels and tires. Estimates are free so you could take it around and get some quotes but looks like a big job . As already stated, mileage comes into play here. Real shame since as you've said these are special cars and getting harder to find.

[jwolf]

Let this one be your, "drive it into the ground," car. Find you another car from the southern US(no rust) to keep to you leave this world. Good luck!

[E82BSM128i]

The mileage currently is 119000 kms and the interior is still immaculate. Everything else is actually perfect about the car except for rust. I also don't intend to drive this in the winter anymore.

The shop said for $1000 they could get rid of it. As far as the other rust on the bumper - could that be taken care of?

[WrathOTM]

It looks like your car is great shape, if it's worth it to you I would fix it. The bumper rust doesn't look too bad, I would however remove it and the liner to make sure the full extent of it is accounted for. Otherwise...well it's not referred to as cancer for no reason.

[Meestah Chow]

Originally Posted by jwolf

Let this one be your, "drive it into the ground," car. Find you another car from the southern US(no rust) to keep to you leave this world. Good luck!

Or interior BC, no salt on the roads.

[ShocknAwe]

Por15

[Donkeyshins]

Originally Posted by Meestah Chow

Or interior BC, no salt on the roads.

Or Oregon / Washington - also no salt on the roads.

[4JawChuck]

My go to for rust treatment is spray rust converter and then liberal coating with fluid film to prevent further corrosion.

Works like a charm and on areas like the rear axle likely never need to be treated again, areas like outer wheel wells where such a coating would be worn off, covering with POR15 is worth the effort and very durable. I use POR15 metal prep instead of rust converter for those areas and remove heavy deposits after conversion (metal prep is a converter as well but uses phosphoric acid not tannic).

Fluid film is the key, it's self healing and benign since it's formulated with lanolin...dries to a jelly consistency and doesn't wash off easily. This step keeps the air out and stops corrosion.

BTW my 128 looks similar to yours except all that rust is black and shiny from the above treatment, did the entire underside in an hour using three cans each of rust spray and Fluid film...looks like black paint from a couple feet away. Luckily my wheelwells are mint so I didn't have to do any POR15 work.