water in oil filler cap

[Jason]

Today I went to replace my oil filler cap because the o-ring had gotten hard making the cap hard to remove, and it was cracked at the bottom, probably from being dropped at some point.

When I disconnected the hose that goes from the cold start value to the filler cap, something like 1/2 to 1 teaspoon of water came out. I couldn't tell if it was coolant or just water. There was also some light brown sludge on the bottom of the filler cap.

Is this something to worry about? Condensation? Block leak? Head gasket leak? Is there a component that can fail and leak coolant into the vacuum lines?

I drained the oil, and no obvious large amounts of water in the oil. Looked like normal dirty oil to me, but I can't say I've ever seen coolant contaminated out. I've got it sitting in glass jars waiting to see in any water settles out.

[Bitsyncmaster]

Make sure you are running the correct temperature thermostat. If your engine has not been run a while at normal temp, I would not worry about seeing a little water there. Using a lower temp thermostat will make the oil milky with water.

[DMCMW Dave]

You probably don't drive it enough to burn off the condensation.

[Josh]

drive the car more, and for longer trips.

[Jason]

The car is driven often. It's a daily driver. Average of 7k miles per year or so.

Though the last drive was for only 1/2 hour maybe 6 days before I replaced the filler cap. The two weeks before that a couple of 1 hour drives and a bunch of 15 minute ones. Before that in the garage for a couple months as there was salt all over the roads.

[DMCMW Dave]

It takes a lot more than you think to burn off condensation like that in the winter. My daily drivers (before we got the Volt) are very often driven less than 5 miles a day have looked like I poured water into the engine in the winter. Not much you can do but drive it more or change the oil more often. Long trips are more important that lots of trips. I actually started taking a much longer drive home just to try and avoid this.