Sludge on inside of oil fill cap & tube

2015 4.0 with 60K miles. Have done the oil changes myself since I bought her at 32K miles, full synthetic 5w30 every 5K.

Did my 60K oil change today and when I took off the fill cap I immediately noticed a light brown sludge on the underside of the cap and inside the fill tube. Hard to tell how far down the tube.

Cleaned the cap and the fill tube as far down as I could get. Finished the oil change, everything was otherwise fine. The cap was on tight when I started doing the oil change. Have had no issues with this truck, don’t remember seeing any sludge at all like this previously.

I have not recently cleaned the engine bay. Coolant level is halfway between low and full.

I’ve skimmed the previous TW threads I could find on this and read some other info online. It could be that this is just a natural condensation issue. We have had a humid last few months, with low dew points and lots of hot/cold temp changes recently. Most mornings the truck is covered in condensation.

I have no white smoke coming out of the exhaust but moisture tends to pool at the bottom of the exhaust tip rim and drip when the engine idles in the driveway.

Also I’ve been teleworking with Covid and so I don’t drive as much as I used to. Maybe I’m not burning off whatever condensation is getting inside the motor.

Any thoughts on this, particularly anything else I should check?

 

That is fairly normal for all makes and model cars.
Depending on the time of year and climate it can be worse.

Looks normal to me.
( Our 2005 Ram w/Hemi 5.7 engine looks like this all the time / ever time)

 

In my experience, that is normal for colder weather, especially if you are making short trips where the engine oil doesn't reach full operating temps (which takes about 2x longer than the coolant to come up to full temp).

I've noted it a few times when an oil change has been needed during the winter months. Summer month oil changes after that had no residue to speak of. Oil gets changed every 5k on my '07, and I'm sitting around 155k miles at this point.

 

I thought only Chrysler products did this.

 

No. It can happen to most any vehicle.
In my experience, our 5.7 engine(s) does this more than our other trucks.

 

Normal.

 

Thanks for the responses. It’s alarming to me only because I’ve never seen it before in the previous 6 oil changes, nor on my wife’s Traverse engine, nor on my lawnmower. Maybe just got lucky with the time of year, weather, and less driving.

 

Short trips where the engine doesn't reach operating temperature long enough to burn off all the accumulated moisture. See it all the time in the rust belt during the winter months.

 

So would a catch can remedy this problem?


Edit: not trying to turn this into a debate

 

Just take a longer way home on your short trips.

 

Tough around here, it’s a rural area so everything is five minutes away or an hour. But hey nothing wrong with a long drive in the country.

 

Not sure this would solve this problem because it doesn’t address the root cause outside the engine. Might pull some of the water vapor out though. I’m not even sure this sludge is a “problem” anyway.