Zing,
It sounds like it is fresh so yes hot water with your 15° should do it, might try a 25° first but don't even think about a 0°.
My opinion only.
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Beep beep, the OPC Roadrunner coming through.
Jon Fleischer
Oasis Pressure Cleaning
(909) 792-2247
Fax (909) 792-5633