Oil appearing in coolant?

Sometimes you need to change the oil more than once to get all of the chocolate milk out of the engine. Are you losing coolant? Also, the engine runs hot in the summertime as long as it is not overheating you are okay. Also, let's run the codes to see what comes up if anything.

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

and

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I popular coolant in the oil problem is when the engine overheated the first time it blew a head gasket, here is a guide to help confirm the issue. Also, can I ask if the radiator fans are running when the temp gauge is at the midway point?

https://www.2carpros.com/articles/head-gasket-blown-test

Please go over these guides and get back to us.

Hi Ken,

Thanks for taking time out of your Saturday to respond to this. Hugely appreciate it.

One thing I'm noticing in a lot of the places I'm posting this question is the confusion betwen oil getting into the coolant, and coolant getting into the oil. When the car originally broke down, coolant got into the oil, and absolutely no oil got into the coolant. It was simply a one-way 'transaction' (based on how this engine is designed). The issue now is the opposite; oil in the coolant.

To answer your questions:

"Are you losing coolant?" - I don't appear to be losing any. The level is staying in the same place, but obviously oil is getting into it somehow.

"Also engine run hot in the summer time as long it is not overheating you are okay." - You're right. I did some tests last night from the advice of another user and after using a laser thermometer everything looked okay. 30-40 minutes of idling and revving, no overheating. Engine itself seems to be running perfectly.

"Also, lets run the codes to see what comes up if anything." - Already ran the codes, I'm getting nothing. Ran them again yesterday, still nothing. Ran a data stream too, nothing unusual happening there.

Already read those 2 articles. I'm getting no check engine lights and I have no reason to believe the engine is actually overheating anymore - that was just my own fault for not properly measuring it the first time.

"is when the engine overheated the first time it blew a headgasket?" - That's what I was worried about. That could've very well happened, but I don't think it is likely based on my current tests. Like I mentioned, I've performed the tests stated in that last link:
- All of my spark plugs have carbon on them (none look "cleaned" - which is typical symptom of a burnt head gasket)
- The coolant reservoir holds pressure (confirmed by doing a pressure test as the service manual instructs)
- Rhe chemical test passes (showing there is no emissions/carbon dioxide in the reservoir, and the liquid does NOT change color)
- There are no bubbles/boiling coming from the coolant reservoir.

I see, thanks for the clarification. there is an oil cooler that I would replace because when the engine is running the oil pressure pushes by the cooler reservoir and into the cooling system. Here is how to fix it. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Hi Ken,

A bad oil cooler was the same conclusion I came to as well (I said "oil pump" in my original post but I meant oil cooler).

I really appreciate the screenshots from the service manual. Very helpful.

As for uploading pictures/videos, I don't exactly know what I could upload that would help. Oil is getting into the coolant, so I could upload pictures of the reservoir showing it's contaminated. But generally nothing else seems amiss. If there's anything specific, you'd like to see let me know.

I'm going to flush my fluids today and maybe get the oil cooler off. Once it's off I was thinking about performing the "water/air test", where you block one end, connect a air compressor to the other end, and fill it with air while holding it submerged under water to see if air bubbles come out, before ordering the part.

I'll let you know how it goes. In the meantime, any further advice would be fantastic. Thanks again.

Yep, the air pressure test should work good, let me know what you find. A video of the test might be fun BTW.

Hi Ken,

Took a while to get back to you! Apologies...

I didn't get around to doing the oil cooler test because draining the oil and removing it takes a lot of effort and I'd kick myself if it wasn't that when I could've tested things more thoroughly first.

Couple of other things;

First of all, I cleared out all of the old coolant that was contaminated with oil and flushed the system with water (I'm going to use something stronger later to get it all out but this will do until I figure out what the issue is). I refilled it back up with coolant and then ran a serious of small tests to see if the oil came back; First of all, I've disconnected the oil cooler from the system. I'm simply bypassing it with a hose now. I then ran the engine for 3 minutes, then cooled for an hour, then ran it for 5 minutes, then cooled for an hour, and then ran it for 10 minutes, and then cooled for an hour. No signs of oil yet. I ran it without any of the fans on, and no heat or AC, and no oil cooler (like I said). If the oil still appears when I do a more prolonged test tomorrow, probably 20 minutes, and then 40 minutes, then I can be sure that it's coming from a place that has nothing to do with those things.

On top of this, I also did a cylinder compression test...

I'm pretty happy with the results but I'd love to hear what you think. They definitely seem healthy to me:

[When facing the engine over the passenger wheel]
Right front:
- 160 PSI
Right middle:
- 170 PSI
Right back:
- 165 PSI

Left front:
- 155-160 PSI (right in the middle so, 157 PSI?)
Left middle:
- 165 PSI
Left back:
- 150 PSI (engine had cooled for about an hour or so before getting around to this)

The service manual has a table of maximum and minimum pressure readings. My range was 150-170. By those results, the table indicates that when the maximum PSI you get is 170 PSI (which is what I got), then the minimum can be no lower than and 127 PSI. My readings are definitely within that range.

Cheers

It sounds like you found the problem, and these compression readings are good to go. Thanks for letting us know, we are here to help, please use 2CarPros anytime.

Hi Ken,

It does appear that way, although without doing the prolonged test (which I'll do today) I'm not going to put money on it just yet. I'll keep you posted.

I'm honestly just glad that every test I have done has continued to rule out the head gasket - which I was very worried was going to be the root cause, and it's an absolute pain to fix in this car.

Just to add some more details; I also borescope inside each cylinder and could see carbon in each one, and no coolant, which is also a great sign. I did not observe any cracks.

One thing I did want to ask was you though: I was under the impression, as I think you were too, that there was only one oil cooler in this car (the one you sent is also the only one I was aware of, and it's the one I'm currently bypassing), but apparently, looking at the service manual, there is another one. One is listed under "Lubrication" (which is the one you sent me) and the other is listed under "Automatic Transaxle", which appears to be different (see pictures - it's #6 on the first diagram). Do you know the difference between the two? Which is more likely to have gone bust? Which is the one that people usually replace?

It's also surprising, because I would expect to see oil dripping from the bypassed oil cooler if that was what was leaking into the coolant, and I've been yet to see that.

Thanks again. It's been fantastic to get a second opinion on this!

Yes, that does look like a transmission fluid cooler, are you still getting oil in the cooling system? If so I would test this part as well.