Every time I scrub down a cast iron engine block, or cast iron exhaust manifold with Dawn dishwashing soap, and rince with water it starts to rust in about 30 seconds as it drys. I don't seem to have enough time to paint the cast iron before this surface rust starts to appear. Is there a better way or some other product I should be cleaning the cast iron with? I have tried a hot steamer also to clean cast iron with but have the same problem with surface rust appearing right before my eyes as it dries. Is there a better way ??