Why does my oil cap look like this?!

What causes this?

 

https://www.youtube.com/watch?v=5HIJfG8YwH4

 

Uh oh. Looks like milk of coolant to me.

 

Looks like blow-by. Consider replacing your PVC valve. This can be normal if you spend a lot of time on idle. If the oil change looks like that then you got some big issues.

 

I'm going to agree with @henryp in that it looks like blow-by. If the majority of the trips you're taking are short excursions shorter than 15-20 minutes and your motor isn't warming up enough, you'll get some buildup like that. You can reduce it by installing an oil catch-can but there's many different schools of thought whether or not one is necessary on a naturally aspirated engine. I can tell you that I installed a catch can when I bought the truck and the oil residue in the can looks like that but I personally don't believe it's necessary for these engines.

-J

 

I've seen worse photos of this around here

Make sure you aren't loosing coolant - as long as your coolant level is stable, it is as the previous posts say, condensation from short trips/engine not heating up all the way/humid environment

 

Blow by is combustion pressure leaking past the rings….that has nothing to do with moisture in the crankcase, which is what you’re seeing.

moisure is a natural occurrence from condensation as the engine heat cycles….most reasonably long trips get the oil hot enough to get rid of that moisture…if you drive a lot of short trips and never get the oil up to temp, this is what you see.

pull the Di stick out and see if the oil in the pan looks like oil or if it looks like milkshake. If it looks like milkshake, you have a big problem…bad head gasket or some other manner of coolant entering the crankcase. If it looks like oil, you’re fine…take longer trips.

 

I just did an oil change and the oil looked totally normal with no discoloration like I saw in the cap.

 

Do you take mostly short trips with the truck?

 

This past oil change I’ve been doing mostly highway miles. And fyi I have just over 80k miles on it.

 

Moisture from the engine not getting up to temp. Usually caused by short trips around town and not enough time out on the highway.

Just clean it out and don't overthink it. If your coolant level isn't dropping slowly don't worry about a HG

 

Many short trips of less than 7 miles. I used to drive 7 miles to work and never had that problem. It did take me about 15 minutes to get to work but at least a half hour to get home.

 

OP could also manually shift the tranny and redline it constantly during short trips. That could introduce other issues though

 

About a year ago my oil cap looked just like this after a particular couple or three weeks when I had almost nothing but very short trips based on some unique life/work circumstances. The next oil change I did, the drained oil looked just fine, no moisture, no coolant, etc. It was just an engine that wasn’t heated up high enough or long enough to cook off ambient moisture as was said above.

 

Your fine. Just moisture not being fully burnt off.