Coolant in oil

A6 All/ S6 All
#1

I am reposing my S8 post here hoping to get some more exposure.

I have always had dissapearing coolant in the S8. No visible leaks, expansion tank seems ok, no misfires and plugs look normal (black/sooty). I did a block tester check for CO2 in coolant, came back negative. Did a coolant pressure leakdown test. maintained 20 psi for 1 hr. No milkshake oil.
I put dye in the G13 coolant in the last maybe 500 km before taking the engine out.
Could this oil in the pan just be from spilled coolant and me turning the engine around on the stand a few times?

This still doesn’t answer where the coolant is going…

Link to pictures on crankcase internals.

https://imgur.com/gallery/MuCAyXj

#2

I had an extremely slow leak on the back side of the w/p. So slow that there was no wet coolant. You could only see the dried/crystallized coolant. Fixed my issue. Just a thought…

#3

I wish it was external, I have zero traces of pink or white crystals anywhere. Checked the underside of the reservoir as well, dry.
But question is…how is there so much coolant in the crankcase

#4

https://i.imgur.com/O1CUpVO.jpg

After looking at it. It looks like splatter. Once you pull the back coolant tube your going to get leak though the heads and figure out all of the other coolant it looks just like a small collection.

When you think about it the coolant wouldn’t be spread like that generally it would be collected though out the oil itself. You know usually when you get oil and coolant mix its milky looking. That coolant looks too green and too spread out to have been there for any time.

Also if you really want to check to make sure. If you have any of the old oil you pulled from the motor send it out to blackstone labs. They can look at the coolant and give you a report of the contamination of the oil. If there was even a small amount of coolant in the oil they would pick it up.

#5

Dunno if this happens on S8, but S6 has a secondary or auxiliary radiator on drivers side.

Mine had an almost impossible to see leak and only white residue gave it away.
This radiator costars mor than the main one.

Also the plastic on the radiator itself is old and brittle and may leak somewhere unseeable, like somewhere around the radiator neck.

#6

I think there are several ways for coolant to get into the oil. One of the main ways would be in the oil cooler it self. There can be a leaking of coolant into the oil when they pass over and interact in the cooler unit itself.