So I've been trying to do as much research as possible because it seems like this semi - common problem pops up in in a variety of ways for people. There is no white smoke from the exhaust, there is a very light knock, the engine runs like nothing is wrong, but the underside of the oil cap looks like light chocolate milk. There is coolant leaking from the thermostat housing area. I can't see exactly where, but it's that general area. I've read people having problems with the lower intake seal, plastic parts on the coolant inlet line to the manifold, and just a good olé blown head gasket. Any thoughts from those with far more knowledge? Also, if it is is a blown head gasket, I plan to take it apart one weekend and put it back together the next. It will be left in a garage the entire time. Special advice? Thanks for all the input.

 

This is the oil cap.

 

You can repair the leak you see but unless the crank case oil shows a milky consistency, the accumulation on the bottom of the fill cap is just vapor condensation on the cool cap due to it's location.
Happens all the time in cold damp weather.
Short run times aggravate the situation.

Good luck.

 

So this dipstick is fairly normal for this time of year? Is there any way to avoid it? Should I actually change the oil now that I see this? I haven't looked down inside to see what it looks like. This is the first vehicle I have ever looked at to have a problem like this. Happy to say that actually.

 

I addressed your fill tube cap only for the milky deposits.
Then said if the dipstick (crank case) oil shows a milky appearance it could be cause for concern.
Are you showing a cold motor photo of the dip stick or a hot motor?
You understand the water/coolant will tend to sink to the bottom of the Pan and separate out from the oil after awhile of setting cold until the motor is run again..
I can't tell exactly but the oil looks ok but there are clear drops of moisture showing separately.
It may or may not be a concern.
A way to tell is seeing a significant amount of water flowing out first as you remove the Pan plug for draining, then the oil comes.
If that were to happen, I would be concerned because the oil pump pickup is the first to take this coolant in on cold starts. Coolant is not a very good lube for the rest of the motor.
A milky appearance is the Glycerin in the antifreeze plus the water that is whip mixed with air causing a whitish appearance on the fill cap because it condensed on about the coldest part of the motor.
Good luck.

 

It may not hurt to do a hydrocarbon test on the coolant.

 

That's a cold dipstick. It hasn't been run since the foam was seen under the cap. I attribute the droplets on the dipstick to the little holes in the dipstick tube. I pulled off the oil filler tube and the inside of the valve covers looked great. I cleaned out the tube, put it back, and am going to be changing the oil tomorrow. Also, I am pulling the PCV valve off to look at it too. I know where it is but not how it comes off. Is it fairly obvious how it comes off?

 

Just do the oil change. Bluegrass' answer sums it up.

If it is indeed your head gaskets, you're in luck because I just did mine. It can be done on a 3 day weekend with nice set of hand tools.

But again, change the oil first. There are milky oil caps posted every day on the F-150 facebook help page and it is common for people who do short trips.