I'm getting ready to install a a new sway bar on my e39 530i. While I was looking around there, I noticed it was a little dirty.

Anyone have any tips on cleaning the undercarriage?

apply diluted APC via spray bottle, let sit, agitate, rinse, BAM

Meguiar's APC @ 4:1 = :D

Thanks, ajnavo61490. I'll give that a try. Just got to figure out how to get under it. :)

If you don't have any jack stands or jacks(use alone would be unsafe) you can use one of the brush you with a telescopic handle to get to far to reach place's

Thanks for the replies.

I was installing a new rear sway bar this weekend, so I wanted to clean it up before I started working on it.

I took the car down to the car wash and used one of those spray wands to clean under the rear of the car as well as I could. When I got it home I raised the rear of the car on ramps. I used a spray bottle of APC and a brush to clean up a bit more. This all raised a new question.

A lot of the rear suspension was coated with a thin layer of soft, tan material. At first I though it was oxidized aluminum. It didn't come off with detergent, but brake cleaner dissolved it.

Has anyone noted this sort of material on their car?

I'm planning on doing a full detail on my car this weekend, so I'll give this stuff a try.

Thanks for the replies.

I was installing a new rear sway bar this weekend, so I wanted to clean it up before I started working on it.

I took the car down to the car wash and used one of those spray wands to clean under the rear of the car as well as I could. When I got it home I raised the rear of the car on ramps. I used a spray bottle of APC and a brush to clean up a bit more. This all raised a new question.

A lot of the rear suspension was coated with a thin layer of soft, tan material. At first I though it was oxidized aluminum. It didn't come off with detergent, but brake cleaner dissolved it.

Has anyone noted this sort of material on their car?


rust protection possibly? have a picture? in some states they automatically add it because of the salt from the ocean or high amount of salted roads throughout the year.

rust protection possibly? have a picture? in some states they automatically add it because of the salt from the ocean or high amount of salted roads throughout the year.


It could be. It's not the black, rubbery substance that I've seen in the past. It's tan colored and about 3 mm thick. It is still soft, sort of the consistency of putty.

This stuff covers the underside of the suspension components. Sort of up the bottom third of the control arms. I didn't notice it on the body, but it could be there, too.

I decided to leave the substance in place for the most part. I was just trying to get the underside clean because I was installing a new sway bar. I prefer to have the components clean.

could just be really dirty cosmoline.