Embedded dirt on the rails

[FeGee3]

I would like to know what people have done to clean the rails/plastic cladding that builds behind the front wheels. My job regularly takes me in to rock quarries where fine rock dust powder and (this year) mud kicks up, making it difficult to keep up with cleaning maintenance. The picture below is post-wash when I thoroughly scrubbed using a generic car soap/sponge combo. As you can see the water drips mask the extent to which the cladding remains dirty, when dry the dirt just cannot be rubbed clean.
Has anyone had this issue and, thus, any recommendations for how I can clean this and protect it more in the future? Thank you in advance for the advice.

 

[Tellthemride]

You probably need to get at that problem area with a detailing brush or even a hard bristle tire brush. Then finish it off with 303 aerospace or other vinyl/rubber/plastic dressing to make the black shine.

 

[arattle]

I would like to know what people have done to clean the rails/plastic cladding that builds behind the front wheels. My job regularly takes me in to rock quarries where fine rock dust powder and (this year) mud kicks up, making it difficult to keep up with cleaning maintenance. The picture below is post-wash when I thoroughly scrubbed using a generic car soap/sponge combo. As you can see the water drips mask the extent to which the cladding remains dirty, when dry the dirt just cannot be rubbed clean.
Has anyone had this issue and, thus, any recommendations for how I can clean this and protect it more in the future? Thank you in advance for the advice.
View attachment 21171

I use a pressure washer to get that type of grime out. Works well for brake dust and in the grille, as well.

 

[PittPa]

Mequiars and Mothers make different vinyl/rubber cleaning solutions that help this. Amazon.com: Mothers 06112 Back-to-Black Trim & Plastic Restorer, 12 fl. oz.: Automotive
I have used this when even after a washing it still has deposits like yours. You do need to reapply this every so often but it helps.