Appears to be oil in coolant- failing head gasket or?

[.bg.]

Background: Have a 96 4Runner with 165K miles on it. It's a 5spd & supercharged. Picked it up exactly 3 years and 30k miles ago.

I check all of the fluids every month. It's always had a very slight amount of coolant loss since I've owned it- generally I've only had to add a splash of coolant every 3-4 months.

I know that everyone swears by the Toyota red coolant, but this truck has had green in it since I picked it up, so I've just been using a jug of Prestone 50/50 "add to any color" antifreeze. I've only used about half of the gallon jug over the last 3 years of adding it.

This week it looked like the coolant was a bit low (about halfway between the low and high markings) and when I went to fill it up, I've noticed what appears to be little bit of oil in the coolant expansion tank. The tank has always been a bit grungy so it's possible I've missed the brown fluid beginning to appear inside of it during my last few monthly checks.

I've come across a couple posts mentioning that mixing the green with the red would cause some brown spots- I don't know when or how my 4runner was converted over to green so I first thought today that it might have just been some old red that had mixed with the green, but while taking these pictures I think it really appears to be oil:





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Here's under the radiator cap- looks pretty clean:



However, if I shine a flashlight at the right angle there does appear to be something floating in the radiator coolant:



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I don't seem to have any other symptoms:

- No white smoke on startup

- Haven't overheated - scangauge is still showing 188-198 when driving around- hottest I've seen is 208 a while back when idling in the 100 degree bama heat with the a/c blasting for about 15 minutes.

- No foam under the oil cap and the oil appears to be the correct color.

- Radiator coolant itself appears mostly clean.


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Seems like I'm in a bit of an in-between spot with only a bit of oil appearing in my coolant expansion tank and no other real symptoms.

So my questions are:

- This is definitely not just a mixing of old toyota red coolant and green right causing this right?

- I saw a couple posts mentioning that oil in the coolant, but no coolant in the oil could just be a failing oil cooler?

- Is it possible I'm just catching a bad headgasket/cracked head very early before any other signs start to show up?


Any insight would be greatly appreciated. Just trying to figure out what my next step from here would be.

Thanks!

 

[JRZEE2000TR4LTD]

Definitely oil. You could send a sample of your oil to Blackstone Labs and be sure to mention your suspicions in the comments. While your waiting for that to come back you could also change the oil cooler oring and bolt seal. That's cheap and easy enough to do. Do a comprehensive flush and see if the oil returns.

 

[StreetCreeper]

Background: Have a 96 4Runner with 165K miles on it. It's a 5spd & supercharged. Picked it up exactly 3 years and 30k miles ago.

I check all of the fluids every month. It's always had a very slight amount of coolant loss since I've owned it- generally I've only had to add a splash of coolant every 3-4 months.

I know that everyone swears by the Toyota red coolant, but this truck has had green in it since I picked it up, so I've just been using a jug of Prestone 50/50 "add to any color" antifreeze. I've only used about half of the gallon jug over the last 3 years of adding it.

This week it looked like the coolant was a bit low (about halfway between the low and high markings) and when I went to fill it up, I've noticed what appears to be little bit of oil in the coolant expansion tank. The tank has always been a bit grungy so it's possible I've missed the brown fluid beginning to appear inside of it during my last few monthly checks.

I've come across a couple posts mentioning that mixing the green with the red would cause some brown spots- I don't know when or how my 4runner was converted over to green so I first thought today that it might have just been some old red that had mixed with the green, but while taking these pictures I think it really appears to be oil:





--


Here's under the radiator cap- looks pretty clean:



However, if I shine a flashlight at the right angle there does appear to be something floating in the radiator coolant:



----


I don't seem to have any other symptoms:

- No white smoke on startup

- Haven't overheated - scangauge is still showing 188-198 when driving around- hottest I've seen is 208 a while back when idling in the 100 degree bama heat with the a/c blasting for about 15 minutes.

- No foam under the oil cap and the oil appears to be the correct color.

- Radiator coolant itself appears mostly clean.


----


Seems like I'm in a bit of an in-between spot with only a bit of oil appearing in my coolant expansion tank and no other real symptoms.

So my questions are:

- This is definitely not just a mixing of old toyota red coolant and green right causing this right?

- I saw a couple posts mentioning that oil in the coolant, but no coolant in the oil could just be a failing oil cooler?

- Is it possible I'm just catching a bad headgasket/cracked head very early before any other signs start to show up?


Any insight would be greatly appreciated. Just trying to figure out what my next step from here would be.

Thanks!

1996 4runners came from the factory with green coolant if I recall correctly. As did my 1997.

 

[.bg.]

Definitely oil. You could send a sample of your oil to Blackstone Labs and be sure to mention your suspicions in the comments. While your waiting for that to come back you could also change the oil cooler oring and bolt seal. That's cheap and easy enough to do. Do a comprehensive flush and see if the oil returns.

That's a good idea. I've gone ahead and ordered their kit. I'll get the oil cooler oring and bolt seal on the way as well.

1996 4runners came from the factory with green coolant if I recall correctly. As did my 1997.

Ahh, didn't know that. Guess that helps narrow it down.


Thanks for the help, I'm going to keep driving in the meantime and can hopefully knock out a oil cooler stuff and a coolant flush next week. I'm guessing it's not the worst thing in the world to have this small amount of oil running through my coolant passages in the engine in the meantime?

 

[PWD4R]

Wouldn't you be losing some engine oil and appear lower on the dipstick? Or am I crazy?


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[.bg.]

Wouldn't you be losing some engine oil and appear lower on the dipstick? Or am I crazy?

Seems like I should be, but I'm guessing I haven't lost enough oil into the coolant yet for it be showing up. Dipstick is still showing just about full at the moment.

 

[Tylerz71]

I would flush it and keep a close eye on its condition afterwards

 

[.bg.]

Update:

I did a coolant flush and have driven it a couple weeks now. I've yet to see anything strange in the expansion tank or radiator.

Also went ahead and did an early oil change and got these results back from blackstone:



So definitely doesn't appear to be coolant leaking into the engine. I don't think this means I'm out of the woods yet, but I'm going to just keep checking the coolant until I see something in it and go from there. I'll update if that happens.

If nothing shows up then maybe it really was a red/green mixing or something else strange that caused it.

 

[PWD4R]

Update:

I did a coolant flush and have driven it a couple weeks now. I've yet to see anything strange in the expansion tank or radiator.

Also went ahead and did an early oil change and got these results back from blackstone:



So definitely doesn't appear to be coolant leaking into the engine. I don't think this means I'm out of the woods yet, but I'm going to just keep checking the coolant until I see something in it and go from there. I'll update if that happens.

If nothing shows up then maybe it really was a red/green mixing or something else strange that caused it.

Looks like it's really about as healthy as it can be. Idk what the top parts are supposed to be at but the bottom ones seem to be excellent and the written part is assuring


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