I just used a product called Peel & Seal. It's in the roofing section at Lowes.
It's just like Dynomat, except it costs about a third less.
Follow this link:
http://www.lowes.com/pd_154017-81326-PS625_0__?catalogId=10051&productId=1018733&UserSearch=peel+and+seal&Ntt=peel+and+seal&N=0&langId=-1&storeId=10151&rpp=24