Oil mixing into coolant

LMAC91

MEMBER
2007 CHEVROLET AVALANCHE
5.3L
V8
4WD
AUTOMATIC
233,000 MILES

I just paid a few days ago to get my real main seal fix on my truck. Also got a new oil change. Now my oil is gone all gone after 3 days of a oil change and my coolant looks like oil in it. Is it possible something wasn’t done right during the time of doing the real main seal?

5 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi,

Unfortunately, the rear main seal would not cause oil and coolant to mix. If you just had an oil change and ALL of your oil is gone, I would think it is more likely that they didn't put the proper amount of oil back in. Even if you have oil in your coolant it is unlikely that all of it leaked in to your coolant. Normally, they blend with each other. I imagine you have had some oil leaking into the oil and now you have an issue with either an external oil leak (like they didn't installed the seal correctly) or they didn't put the oil back in.

Either way, I would fill your oil ASAP and then inspect it daily for external leaks or check the oil level. Also, how much oil do you have in the coolant? Is it just some on the top of the coolant or is it completely mixed?

Let me know what you find and we can go from there.

https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

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Sunday, August 18th, 2019 AT 10:50 AM

LMAC91

MEMBER
3 POSTS

I just got the real main seal fixed because of oil leaking. Got a oil change after a from the same place I normally go to with my company work van an personal vehicles called grease monkeys. Can’t tell how much oil got mixed I just know it’s brown an milky looking in the coolant reserve box. Also looked under truck an see look leaking off the 4x4 block under the motor right where the main seal is. Guess I’m trying to find out is this a problem on me that just happens or could it be because the real main seal got put in wrong or the gaskets running to the oil cooler got pinched an cause oil to go into coolant? Oil is definitely all the way out my truck my truck though and they had to take my motor out to fix my real main seal because I have a 4x4.

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Sunday, August 18th, 2019 AT 12:51 PM

KASEKENNY

MECHANIC
18,907 POSTS

Coincidences happen in this industry every day but this one is not a coincidence in my opinion. I would get enough oil back in the engine to take it back and have them check it out because I suspect the seal has failed either by how it was installed or just an inferior product.

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Sunday, August 18th, 2019 AT 5:05 PM

LMAC91