Insert bearings
 

Starting my Burtz build I got 2020cp Sealed Power inserts, and started fitting them. Haven't assembled an engine in a while and half of them were as I remember, and half were like in the picture. Darker, rough powdery feel, like they're oxidized. Can I use them cleaning them up or send/toss them back?

Re: Insert bearings
 

Usually that's a sign that they may have been exposed to moisture while being stored.
Probably not worth taking a chance. Just replace them. Or return them.

Re: Insert bearings
 

Send them back.