Lots of oil/coolant in manifold

[D01SS]

I never posted on here much, but I'm in need of a little help or guidance. Over the last year or so my mileage is dropping drastically (my calculation, not the dash) and I am averaging about 12.5 MPG and majority of my driving is highway. For the most part I was constantly averaging 16MPG with a leveling kit and 33's. Last night I decided to change the plugs, wires and air filter and I took the intake tube and throttle body off just to clean up stuff while I was in there and found a ton of oil and what looks to be coolant. I personally have never seen this much oil inside an intake manifold, normally it is just a light film. I have been going back and fourth for a few months with getting a new truck or just keep making repairs to this one since its been paid off for a few years. I know this is not something that can be solved over pictures on the internet, but does this look to be possibly something that is pointing to a larger problem. I checked the dipstick and oil cap and I did not see anything unusual. Plugs also did not look to be anything abnormal either when I removed them. The truck is a 2014 with 142K on it. Thanks in advance for any help. 

Edited February 25, 2022 by D01SS
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[CamGTP]

If the oil has no coolant in it then all of that is condensation mixed with the oil. The intake manifold has no coolant going to it at all. So the moisture that is in the crank case is being sucked up by the PCV system.

 

If you want to take another two steps in the tune up process you can do the following.

 

Run a can of the GM GDI cleaner through the intake or any of those GDI top end cleaners. Run a can or two of seafoam through the fuel tank for the injectors. Then replace the upstream o2 sensors with new OEM sensors. At 142,000 miles they are technically over their service life in my opinion.

 

Also if you can look at a live data scan tool, see what the alcohol content of the fuel is. If the sensor is not reporting an accurate value, then fuel usage can go up. Like for example you are using regular unleaded with a E10 rating, it should report roughly 5-10% depending on time of year but it's it's saying 30% or higher then there is an issue.

[pokismoki]

only place where oil and condensate enter the manifold is at the pcv port, try a new pcv valve,  yours might be getting hung up due to sludge in the valve or its just not checking the valve in cold weather

 

 

your milage sounds fine to me,  it could be dropping due to the refineries changing blend, also if you have  175 engine stat, in cold weather this causes it to run richer

Edited February 26, 2022 by pokismoki

[D01SS]

I appreciate the quick responses. I’ll give the GDI cleaner a try and change out the O2’s and get a new PCV valve.