I bought this to clean 2.5 year old carburetors that were clogged with ethanol. I also bought a gallon of Gunk Parts Cleaner for comparison. I cleaned 4 carburetors from a boat engine so I could compare the two cleaners evenly. First, both cleaners have a very strong odor and smell like your hands when you're not wearing gloves. The first test I did was installing the completely disassembled carburetors overnight. Both purifiers did a great job of cleaning carbs. My next test with the 2 carbs I had left was to see how good the cleaners were in less time. I soaked both disassembled carburetors for an hour. In this test I found that the Berryman cleaner performed better. The Gunk Cleaner still cleans really well, but I found I had to scrape a little more residue off the bottom of the bowl. What I liked most about these two cleaners and why I only chose Berryman was the housekeeping. Using only dish soap and a bucket of water, Berryman's cleaner cleaned the parts very well and left no cleaner residue.