Not really sure...I wash it religiously right now. The day I bought it I went riding and didn't really give it ****, but got a couple globs of mud on the back. I got home, washed it off at the car wash and put it back in the garage. I noticed that spot and tried simple green on it, but it didn't work. Then tried bleach...didn't work. Tried tire cleaner and it took a good bit of it out, but its still got a tan tint on the plastic about the size of a quarter.