Dirty spots on new rotors

[r32]

Picked up some new Centric rotors for a 5th gen brake upgrade. Washed them with warm soap and water yesterday to remove the rust preventative oil material from the factory, dried them off, and put them back in the box until I can install them this weekend.

To my surprise, I noticed today that two of them have spots now. I'm guessing that oily residue leaked out of the air vent holes. Tried cleaning up the spots with brake cleaner. Didn't work at all. If I rub my thumb vigorously across the surface, a little bit of it seems to come off. About rubbed the skin off my thumb though, so that's no good.

Something to be concerned with, or just give it one last spray of brake cleaner and towel wipe before I put the calipers and wheel back on during install?

 

[Fern]

Probably just oxidation. It will be fine. The pads will rub that right off the first time you apply the brakes.

 

[TechWrench]

Pretty sure those marks are left over from contact with the plastic sleeve that they wrap around the rotors for rust protection during shipping/storage. Also, I suggest, IMHO, that you clean the shipping oil residue from the rotors using brake clean instead of soap and water. Less chance of any moisture causing rust problems on the new surfaces. I use brake clean to spray them down and then use compressed air to dry them off. Also, I try to not clean the shipping oil of them until just before I am ready to install, less chance for rust to form. Even though once installed, rust will start its attack almost immediately.

 

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Are you sure you want Centric instead OEM JDM original rotors? Most aftermarket rotors are made in China or Taiwan...