1) The search button works. :D
2) Greased Lightning.

I figured at one point this topic of transom cleaningwas covered, but I have my corrosivity concerns so I decided to start the thread. The search button(here on OSO) is another good suggestion.

I did like the Greased Lightning product that seemed to work the best among the spray bottles for the carbon stains.

I use ZEP citrus cleaner. Not too aggressive and works really well especially on oil and greese...

we use Dawn dish soap just squirt some in and brush around best thing for grease and oil try it you will like it and it is cheap also will not hurt paint and non toxic

Zep and Bada Bing work great..

i just came back from detailing the boat and i wanted to get my exhaust tips clean.i tried spray nine,bleach,goof off,slime,etc..... and there was a guy with an old hammond that really runs well.it looks brand new,he has a merc540 bulldog w/cmi exhaust and the same 4"tips as my boat.he suggested CLR!!!!! WELL I PUT SOME IN A SPRAY BOTTLE.BINGO WORKED LIKE A CHARM