By: RayMan (from BimmerForums.com)

There has been numerous threads written on the subject of removing the dull gray finish on E36 sideskirts. Those of you that have read these other threads might be asking yourselves why another thread on this highly-documented topic. Hopefully, these comments will offer people thinking about doing this mod an easier and more effective technique.

The similarity with all the techniques used to remove this grey paint is the use of either some chemical solvent (most commonly, Castrol SuperClean) and/or abrasive devices such as bristle brushes, sand papers, steel wools, etc.

I am not quite as brave as some others who used sand paper or steel wool on their paint surface. I guess the advantage using these highly abrasive tools is that they are really effective in removing the unwanted stuff, whereas, a soft brush would require a lot more elbow grease.

My objective when I was removing the gray from my sideskirts was to minimize the wear on my hidden paint finish. Therefore, I figured that the use of a soft brush would be much gentler to the paint than that of a harder brush (or sand paper & steel wool for that matter). I used a dishwashing brush I picked up at IKEA for about 2 bucks. The biggest drawback with such a soft brush is the additional physical effort required.

So here’s the trick. Several threads advise to spray your side-skirts down with Superclean and let it sit. If you let the degreaser sit for a very, very long time (i.e, 2 to 3 hours) the gray stuff actually softens up a lot. The key thing is to keep the skirts wet with degreaser for the 2 to 3 hour period. If you spray on the degreaser it will probably dry up in 5 to 10 minutes depending on temp and humidity conditions. To prevent the degreaser from drying up, stick a layer of paper towel to an area of your sideskirt that is covered in degreaser. Then, spray more degreaser on the paper towel to make the paper towel stick solidly to the skirt. The wet paper towel will hold the degreaser against the grey paint and slowly soften it up. Try to get rid of any air bubbles between the paper towel and the skirt. While you are waiting for the degreaser to do its job you should respray the paper towels with SuperClean 2 or 3 times to make sure its wet at all times. Do this in a vented and shaded area.

Then remove the paper towels on a small section (1 to 1.5 feet) and start scrubbing with your brush. Working the skirts with a brush now will be a lot easier as the grey paint will have softened up. Make sure you keep the area you are working with the brush nice and wet with Superclean.

After I prepped my sideskirts by soaking them, it only took me about 20 minutes to scrub off the grey paint for each side using a soft brush.

When you finish removing all the grey paint, hose the skirts off well. If you have access to a buffer, buff the skirts with a good cleaner-wax. I spent about 1/2 hour on each skirt with a buffing wheel so if hand polishing is 5 to 10 times less efficient...you do the math.

The final result on my car was good enough not to need clear paint.