Did you run the engine and warm it up just before draining the oil?
If YES, then I would expect any contaminants (fuel,water,coolant) to be completely mixed in the oil and the drained oil would have a 'coffee with creamer' look to it in the pan. It does not make sense that some of the oil looks fine, but some areas of the drain pan look like yuck.
I would guess that something was in the drain pan and mixed in when you drained the oil.
Was the drain pan clean when you drained the oil ?
Notice any coolant loss.?
We need this info before jumping to conclusions.
Has the OP confirmed that he’s 100% sure the pan was clean before draining?
I‘d recommend running another of your already-short intervals and see what you see.
I warmed the engine up before the oil change, and as for my drain pan I always clean it out with a blue disposable shop towel when done. Before using it the next time I check it and wipe it out again if needed. Does anyone think this is the culprit? The stuff that’s in the drain pan floats around along with the oil but just near the bottom of the drain pan. I didn’t notice anything till I got to the bottom of the drain pan.
If not already done, I would send 3 samples- 1 with the bulk oil and one of the "sludge". I would also send a coolant sample for analysis just as a cross check.
If you have any remaining, I might suggest running a field 'crackle" test. ( In a safe area with PPE, heat a nail to cherry red and plunge it into some of that "gunk" and listen for the "rice crispies' sound. That indicates water is present) I would also perform a blotter test with a coffee filter and look for any debris or particulate solids (not wear metals) and an olfactory test ( smells sweet or sour with sweet usually indicating coolant)
Just ordered 3 test kits so I’ll be sure to report back what they say. Regardless I’ll bring it into the shop this week to start a history on it. I'll keep you posted when I try the crackle test this week.
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IIRC its been over the course of 6-8 months that the antifreeze got to this level. I assume that's more than enough time to cause this. If that's what most everyone agrees on (that or moisture) then I'll start drilling down on the tips you guys gave me and get back to you.
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Side note: Could the dealerships TSB fix on my oil pan gasket have something to do with this? I got it back from them on my last oil change and changed the dealership oil back to Ultra Plat the following week after I got it back from the shop. Maybe something got in the oil pan when they were originally fixing it?