I used Dawn Power Dissolver tonight for the first time on my 55AX. It worked well. I had a lot of burnt on Castor on my engine. It took 3 sprayings with 20 minute soak cycles, then a nylon brush (toothbrush is good, too) to get it clean. The last of it came off better when I ran it under warm water and used the brush on it one last time. I got the fins and around the glow plug very clean. Remember to plug off the carb and exhaust ports to keep the stuff out of your engine. The smell reminds me of a cut-strength OVEN cleaner.