Originally Posted by Brian Carlton

Now, that is the proverbial question. I did not have the proper cleaner and I used Dow Bathroom cleaner (OK, you can stop laughing now). It did an acceptable job getting foam down into the fins. Nothing else mechanical can get down there.

What I would really like to find is come "condenser cleaner" that the HVAC techs use in the field for cleaning a/c condensers on houses. Now that would be the ticket.

If you do find something that gets it thoroughly clean, please advise.

When done, take the radiator and hold it up to the sun. You can either see through the fins right to the other side, or you can still see bits and pieces of crap in the fins. I got about 75% out of mine, but, it was not perfect. A proper cleaner would have worked wonders in a much shorter period of time.