I just tried rubbing alcohol and a scotch brite pad (el cheapo). While it did take off the darker, heavier deposits, its just not cleaning up the rest of the area. Maybe the rest that I am seeing just simply can not be cleaned? My stepfather has some alum. polish that I'm gonna try in the near future. Also tried goof off. Although I didn't try it on the heavy deposits. Either way it didn't work but it might on the heavy stuff. Once I get it as cleaned as I can get, I might switch to the clear coolstop pads.