I was fixing up an old truck. Found rust on the fenders. Tried using white vinegar. Soaked some rags in it. Placed them on the rust overnight. Next day, rust wiped right off. Ready for primer and paint.
Learned that the hard way cleaning some old tools. Vinegar eats away rust, but it also eats the good metal if you forget it. For small parts, an hour or two is plenty. Always rinse with water and dry it right away, then oil it. Leaving it wet just lets the acid keep working.