I took apart my SH 28 nitro engine but some parts inside turned brown in color and I'm not sure if its corroded or got rusty. I've seen pictures of other engines after and they still look shiny and clean inside after a few gallons. I always use after run oil so why does mine look like this? Otherwise it still runs fine but it just looks ugly inside.

from what I see I would say yes it looks like rust

Yes. Not a happy engine. Are you using after run oil?

I always put drops of after run oil down the glow plug hole and carb every time I'm done for the day. If I've been doing that then I'm not sure how this happened. Otherwise it still runs just fine. I recently took apart my OS 18TM on my Revo and it looks the same too. When its tuned properly it still has lots of power and top end speed. If its rust shouldn't it affect the performance of the motor?

If you live in a humid area, you can't keep a SH mill rust free. Except for tearing it down regularly. That's the only way I could keep mine looking fair. They are just very rust prone.

It's the cut of steel manufacturers use, looks like a used normal engine to me. If it bothers you pull the crank out and hit it with a steel wire wheel on a dremel, then hit it with a polish wheel and some mothers.

I just wanted to know if it was rust or some kind of corrosion so its good to know this is normal. It doesn't really bother me if it looks like that as long as the motor still works good.

It's normal, no worry.

looks like castor varnish...what fuel do you use É