Red/brown residue powder in turbo and exhaust
 

While replacing my turbo (with a new GT2854R) I found an odd red/brown soot in the turbo and dp.
Any idea what it could be?
https://cimg2.ibsrv.net/gimg/www.mia...2e49401462.jpg
https://cimg3.ibsrv.net/gimg/www.mia...6893435028.jpg

It looks a bit too red to be rust but the turbo did sit for a while when I had the engine rebuilt recently so it could simply be rust.

Are you using fuel or oil additives?

I've seen that with certain gas, used to be go-mart gas. But that was back in the 90's, haven't seen it in decades.

No fuel additives but I did use break-in oil after the rebuild which contained added zinc and phosphorus I believe. Would that cause this red residue?
The cars done around 3000 miles and two oil changes since then though.

I've seen it before too but I'm not sure what caused it in mine.

I thought I remembered hearing/reading about certain octane boosters causing red soot like that in the exhaust. Those bottles you can add, or certain higher octane fuels would cause it.
This was years ago that I heard about it though (like late 90's), so YMMV.

I think it was Techron or something else (another brand) that caused it for me. There was one that left purple too. I would say it is an additive.