Kind of Milky Oil. Am I Right to Not Worry?

I changed the oil in the B.U.T.T. today.  It's a 2000 Excursion with the v10 and just about 130k on it.  When I opened up the oil fill, I saw what looks like white lithium grease in the cap and down the filler neck:

The dipstick didn't have any beading on it and the oil looked like good-but-used oil - no milkshake.  The drained oil didn't appear to have any water in it and I got oil from the first drop out of the pan.  I cut the filter open and didn't have anything remarkable in there either.  Nothing looked like anything but 3000 mile old oil with the solitary exception of the filler neck and cap.  My assumption is that since it's cold out and that neck is so long, I'm getting condensation there on short trips.

Am I right to not be worried?

UOA. Seriously. That will show signs of coolant leaks at such tiny levels to be helpful. Lots of cars build up moisture in places like that in cold climates. Sometimes they don't get hot enough up there to burn off the water and you get this. 

If you have any questions, a test kit is usually around $20 and takes a few days to get results. Its worth the peace in your mind.

EDIT: keep in mind, small coolant leaks will usually burn off the water in the bulk of the oil if the engine reaches operating temps. Thats why UOA looks for the carrier salts for the inhibitors instead of actual water.

In reply to bobzilla :

And now I feel like a complete moron for not having thought of that on my own!

That's a great plan of action.  I'll run this oil for a little bit and send it out.

Probably condensation. Doubly true if you do short trips that don't warm up the engine completely. I get it in some of my vehicles that sit a lot. 

wae said:

In reply to bobzilla :

And now I feel like a complete moron for not having thought of that on my own!

That's a great plan of action.  I'll run this oil for a little bit and send it out.

It's what I did for 5 years and they trained me really really well then abused me. But like a sponge, I absorbed all that info. If you do it, send me thereport and I'll be more than happy to interpret it for you. 

Yeah, I had a similar issue on my car a few years back.  One obvious issue.... the car has no radiator!

I suspect it was the result of taking short trips in the winter months.  It never got hot enough to burn off the condensation.

Could also be a bad/clogged PCV

My 05 f150 does the same thing with a similar oil cap on the 4.6l.  Has happened every winter for the past several years that I have noticed and nothing bad has befallen it yet. I think condensation.  

How often do you run it between your house and the shop?  That can’t be long enough to get the oil fully up to temperature.

I've owned a few Fords with similar concerns. Like others have said, PCV failure or cold starts without running at temp for a while can cause this.

For peace of mind I've done an oil analysis coupled with checking the coolant for combustion gases (using a cheap tester like this)

I will give the pcv system a check - that's definitely something worth looking at.

This is unusual for me, though: typically in cold weather the truck gets fired up to go driving for an hour or so at a stretch.  Since the kids haven't been in school and I've not been going to the office, it usually runs for 15-20 minutes and gets shut down again.  It gets all the way to normal operating temp, but not for very long before it sets for a spell. 

I'm going to continue to not worry too much about it.  My stomach dropped when I took that cap off, though.

In reply to wae :

The first time I saw that on a oil cap, I had the same reaction! Went through the same checks, (new to me car... guess they had cleaned that off befor I looked at it!) But since I drive more than the po, I havent had that show up again. Plus, Its not usually that cold down here, now that I'm staying local!

It's winter.  ALL Mod motors have lung mustard in the oil fill cap region because water vapor condenses there.

Yup

That is normal condensation on piston-engine airplanes especially in cold weather with short trips. After 45 minutes or so you don't have it. I imagine that's what it is. it looks exactly the same.

Mods are a "special" case because the plastic valve cover doesn't conduct engine heat very well, and the placement of the oil fill is in the airstream from the radiator, so it's always got cold air blowing at it.  There isn't enough oil splash from the valvetrain to wash it away.

If you got the engine HOT and let it idle for 20-30 minutes, for minimal airflow and maximum underhood heat soak, it may go away.