Thx !!
The oil was removed with ot8 it's never let me down yet
No I never pre treat drives but I always turbo nozzle than FSC to get the roots out, yes I hypo afterwards if the area had lots of moss, algae or lichen.
On the roof I pre treated with algoclear at the back to help start the process 10 days before cleaning applied with scrubbing brush converted for WFP - we also applied another treatment after cleaning