This can't be normal
 

https://cimg1.ibsrv.net/gimg/ls1tech...2eecf1104e.jpg
https://cimg6.ibsrv.net/gimg/ls1tech...4e2e33bc7c.jpg200k ls1
was this rust gunk clogging my system

What does the rest of the cooling system look like? Or what's left of it...

It looked like dog doo. Ran the prestone radiator flush a while back to flush the dexcool out, and no matter how many times I flushed it I'd get oil in my coolant, no coolant in my oil though. She's all apart for the winter for a full teardown, and get denmahfiedhttps://cimg0.ibsrv.net/gimg/ls1tech...d727af2261.jpg

Mine looked the same at 194k.

Oil or tranny fluid?

If you still have the power steering cooler, delete it

Looked like oil, no PS cooler here.

Check coolant for exhaust gas.

This is going to be pretty difficult with the engine disassembled.

Good if you don’t have one. Everything you described and photographed is EXACTLY what you get when you don’t delete the PS cooler on a F body. The power steering fluid gets in the coolant through the cooler. Looks like diarrhea. Is very obviously oil, but no coolant getting into the oil. You’ve already got the motor out. If you’re gonna do a rebuild, have the block hot tanked.

Definitely the plan on the hot tank , debris fell into my cylinders when pulling the heads.:barf::barf::barf:

Now just tear it all down , hot tank rebuild , fuel lines and Walbro 400 , 4l80 , and the 7876 Denmah

Don't be so sure it was oil you were seeing, I just went through the same trouble with a neglected dexcrap system. The weird looking oily crap didn't stop until I cooked the living crap out of the system. I tried flushing it over and over and it never ran clean soooo I ran the engine at idle with the rad cap off until it boiled over. Unreal amount of crap cooked out and finally no more oily mess in the rad.

Dexcool can make a mess like no over, it should be banned from the industry. Problem is it makes these car companies big money because it doesn't tolerate neglect. You neglect a dexcool system and it runs low you can make a crazy mess very quickly. I had a 99 TA that had a small water pump gasket leak. Over a few weeks the system went acid and it ATE the rad cap rubber seal. Insane stuff.

Note to self; NEVER allow Dexcool in ANY vehicle of mine...
GOOD heads-up! Thank you!

Normal. all the composites look like that with mileage.

I just saw the same thing. I blamed it on dexcool and the ps cooler that I deleted that had coolant in it.

https://cimg9.ibsrv.net/gimg/ls1tech...c4d0d745e0.jpg

Upon further inspection ... https://cimg6.ibsrv.net/gimg/ls1tech...db0709c161.jpg

Any chance someone may have used that CNC block repair crap from the auto stores? That shit makes it fair amount of mess, too.

Radiator trans cooler can leak oil into the coolant also. I personally prefer an external trans cooler only and to take the radiator cooler out of the trans cooling system by bypassing it.

I see that on head gaskets all the time (crud build up) don't get caught up in it.

It's possible on the block repair crap from autozone, bought with 120k , now has 180k.

I bypassed the radiator and ran an external trans cooler.