Aloha,
Below is what I've done with my GLE. It works really well and is not difficult at all. You just need a little time and patience.
Tools:
- Meguiar's Hot Wheels Aluminum Wheel Cleaner
- 600 grit sandpaper
- 1/2 inch wide cut piece of a used gift card (see attached photo)
- Nitrile gloves
- Cotton or microfiber towels
REMOVING THE GRIME AROUND THE RUBBER NIBS
1. Make sure you put on the gloves.
2 Cut approximately a 2" x 2" piece of sandpaper.
3. Wrap it around the gift card cut piece.
4. Wet the sandpaper with the wheel cleaner.
5. With the edge of the card/sandpaper, move it back and forth to loosen and remove the gunk around the rubber nibs. The firmness of the gift card behind the sandpaper allows for enough pressure to be applied on the grimy surface. The card's flexibility also helps in bending it to the shape and contour around the rubber nib.
6. Wipe off the dislodged gunk.
7. Repeat for each nib on the runningboard.
CLEANING THE ALUMINUM SURFACE
1. Once all the nibs have been cleaned, it's time to clean the aluminum surface.
2 Cut approximately a 2" x 2" piece of sandpaper.
3. Wet the sandpaper with the wheel cleaner.
4. Start rubbing the stains and grime from the aluminum. This step also gets rid of any scratches that you may create in cleaning around the rubber nibs. Recommend rubbing in one direction only (front to back) to give it a uniform .... almost a brushed aluminum appearance.
5. Wipe down clean with a damp towel.
6. Wipe dry with a dry towel.
That's it.
See before and after photos below.
Just additional info: With 600 grit or finer grit sandpaper and with care, one could avoid heavy scratches. Just need to apply enough pressure to slowly remove the gunk and a lot of patience to continue doing it until it is all gone.
Afterwards, I applied sealer on the runningboard to help protect it from the elements.
I've tried other methods with cleaners, polishes, brushes, etc. I've read on the web but for the grime I had to remove, the method I used above worked really well.
YMMV.
I just need to keep on top of it now that I've cleaned it and not let it get that bad again.