This solution is rather pricey and falls under the category that Tabdoo16 mentioned, but a company called Damon Chemical sells a product labeled SF-77. In essence, it is an acid based cleaning solution. I used it cleaning the grease and oil off my 72 Chevelle. Granted, I had to dilute it, but it in conjunction with a pressure washer worked quite well. However, if you're bold enough to put SF-77 on straight, don't let it sit there too long. We put it on straight on the family motor home and it started taking the paint off. Boy, it was clean though...
