Instead of towing to the coin op I rented a power washer with propane burner. It heats the water to close to 200 degrees and you get various nozzles to use. I scraped the heavy crap off first to eliminate as much as possible. I soaked the frame with Gunk engine cleaner where it was greasy and used Spray nine to soak the dirty areas. I used my engine hoist to lift the front end up about 5' off the ground so I could blast under neath. I also pulled the wheels off to get all around the assembly. It worked well and got rid of pretty much all there dirt and grease. I have a gravel drive way so I had no issue with harming the asphalt.
Mark