I just looked at the posters locations. Rust isn't a big problem for those of us on the left coast and pretty much not at all for those of us in AZ and NV. Rust requires moisture in the air. I think that's why Cool Power is used a lot here and no one is having a rust problem?? When I have seen people posting questions about rust and after run oil I always look to see where they live. I never add any Castor oil but I do like blended fuels with a little added in by the manufacture, I don't always run my engines dry or use after run so a little Castor my be another reason I don't find rust in my engines. Just another one of those little things to think about.