Dave try autoglem debris remover my car is always covered in particals and sand im parked on a industrial estate 5 days a week got to eash at least 3 times a week no scratch or swirles i bey 5lts a time and mix with maguires NXT shampoo no problems hope this is of some help Andy F
Thanks for the reply but they are the fixed rails mine fit to the roof without roof bars it's just a plastic cover that covers the fixing bolt I think I have a part number as Audi do a repair kit ( I hope) cheers again