Looked for the non-foam type, didn't see them, so I got the ones pictured. I'm going to give it a try. You sprayed the underside of the oil pan with dish soap and let it soak in for a while then used a bucket of soapy water and washed it?
I'm thinking Dawn soap in a bucket of water?
The underside of the oil pan probably has a pound of grime on it, that would be hard to clean off.
I wonder if Purple Power or Simple Green would be a good choice over Dawn in a bucket.