The red bottle that looks like snake oil. My dad showed me an article where they developed it for radial airplane engines. The valves would stick when they tried to start them up. The valves would actually break.So this was the answer. I found that if you had a stuck lifter or engine tick this stuff made it go away. I also had luck with getting old cars with a carburetor to run good when they had sat to long.My Chevy sat in a parking lot a bunch and this stuff really helped out. I think it is good for guns also.