When we purchased our first New TT in 2000, the service manager advised us to wash the rubber roof only with laundry detergent. We did this for the 10 years that we owned it and it still looked new with no leaks or other problems when we sold it. I still do this with our Flagstaff today and was wondering if anyone else has heard of this or does this? He told me that the laundry detergent is not harsh on the rubber and it will not harm it or the sealant.