My car has terrible buildup underneath from years of leaking pan gaskets and valve covers. I've tried spray degreasers but elbow grease seems the only way to dissolve it. Any success with other cleaners?
Diesel fuel in a spray bottle and scrub brushes....wire, plastic, etc. Microfiber towels. Lots of time. And pain.
Put it on a lift and hit it with a pressure washer. You'll wear much of what comes off the car ,no way to avoid it! .
I’ve used Super Clean aerosol (it clings better) and Griot’s Oil and Grease Cleaner with good results. Didn’t even have to drag out the power washer.
All the above cleaners will work. It’s a slow, dirty, laborious process. Take your time and let the cleaners soak well even overnight before scraping.
If you have some $$ to spare, dry ice blasting does wonders to remove softer contaminates. It could cost $1,000 to do a thorough job. There's a place here in Pa that does it: https://www.facebook.com/actdryice/ Impressive, but costly. If you want to DIY, scrape as much as possible off with a putty knife or old kitchen knife.... that'll make the final clean with solvents or pressure blasting that much easier. And the solid scrapings are easier to clean up vs lots of dissolved grease.
Scraping off as much thicker stuff off as possible helps a lot. The degreasers cut through better if its not as thick. I had good results using heavy duty oven cleaner. Easy Off is good, but you can get the same stuff at Family Dollar in their store brand cheaper and works just as good. It will burn your skin and eyes, and take your breath away, so use safe protection. Spray the oven cleaner on pretty heavy and let it soak. The can has recommendations for how long, seems like it was several hours or overnight. When I was ready to wash it off, I wet it down with Parson's sudsy amonia to get it soapy again, and hosed it off with a spray nozzle and scrub brushes. After that, respray with amonia and wash and scrub again. (amonia is strong too, use protection with it too) Try to keep from leaving these chemicals on aluminum very long, as it will discolor it. I discovered one thing. All of that grease and oil preserved my floor pans. After the above cleaning, the pans looked like brand new metal where it was covered with heavy grease and oil. It's definitely a messy job laying on your back, using a creeper when you can. I put my car on 4 jack stands to get as much room as I could.
I would use plastic scrappers to get the heavy crap off first, like someone else has said. You would hate to scratch the floor pans if they are really nice under all that grease. Best choices are the diesel fuel or mineral spirits. I did just used a product called "Formula 88" a degreaser I got at a Advance Auto Parts and it work pretty darn good. Fernando
Some people said I was nuts (which may be true) but when I lay under the car and scrape the crud off, I cover myself with one of those thin light plastic bags they use at the dry cleaners. That keeps the stuff out of my face and beard and clothes. It's light enough so you can see through it and doesn't impede your breathing.
The one thing that I have found to be the best help in removing underside gunk is heat. The warmer/hotter it is the easier it is to clean off. I like to use a halogen work light for my heat source. What I have found to work best is to heat the metal up from the opposite side (if possible). Once the metal is warmed up the gunk will peel off with a putty knife. Keith
