Originally posted by Sport_Pilot
Crank shafts on modern engines are high alloy steel. So high it's almost impossible to rust. In fact the rust won't even be red, but black or grey just as when stainless steel rusts. Most likely you see varnish on your crank.
I guarantee the crank is rusted. The rust is red and the crank is pitted. There is zero varnish on it. If there was even a hint of varnish, it would most certainly have dissolved after a 6 month bath in mineral spirits.
Want some pictures?
John