Assessing Crank Wear: What is this?

[Moto-Mucci]

Bought a new bottom end with 74k on it and tore it down yesterday.

Motor came out of a cabrio that has been sitting for a few months at least.

Below is a picture of the crank with what looks like a liquid stain on it. It's on a few of the rod bearing areas, and in the same orientation. This lead me to believe that it was just due to it sitting.

However, we tried to brake clean it off and it wouldn't come off. Can anyone assess this? My worry is that it's a hot spot.

[Burnera]

could also be a 'flat spot' where the concentricity isn't perfect. You would need one of those really acurate centering calipers to know for sure.

[jlevie]

That looks most like corrosion a corrosion mark and when you have the crank polished it will disappear. But before doing that use a micrometer to measure each journal at several points and compare those measurements to the published wear limits.