steering rack slight surface corrosion/dirt

[Z2TT]

Hi.

I got a steering rack I'm putting in a car, it has slight black corrosion on the shaft, it did not leak apparently.

I'm wondering is this going to leak out from here and how would I go about smoothening it up.

I was thinking a very fine sandpaper 1500+ but feared removing material from the shaft would make potential of leak even bigger.

What is you guys experiences

Cheers

[Xauterus]

Post some pics, will help