Hi So far I have washed my car (Mercedes GLA 200) in a wash road (Best Carwash and Softcarwash). I am now thinking about changing to an SB-wash box (Softcarwash) to save the paint. However, all wash boxes near me do not allow hand wash. So I have to use the existing brushes and shampoo. I have already read often that this can cause damage in the paint (old brushes, dirt in the brushes). Is a good wash road or an SB-washbo x (Softcarwash) with the existing brushes better for the paint?