foamy oil?

I think I've read threads on this forum about foamy-looking oil. I just added some oil to my 2000 Hyundai Elantra 2.0 (88,000 miles) and the oil on the underside of the oil fill cap looks foamy. Sort of like the head on a Guinness Stout, only not as tasty.
Am I right in thinking that coolant may be leaking in? And if so, from where does this happen?

Thanks!

Pecos

 

You may have some garden-variety gunk on the underside of your filler cap, but water (coolant) in the oil will do that, too, as you heard. Normally it will also be noticeable on the dipstick, sometimes referred to as "peanut butter" or other descriptive names. Are you losing coolant, i.e. needin to top off the reservoir?

Water/coolant in the oil is generally from a blown head gasket.

 

It's possible to get that occasionally during weather changes or changes in driving patterns, especially with both
However, if definitely warrants more investigation
Look for other signs like T_G mentioned

Switch over to Castrol GTX
Much more Guinness-like
Mmmmm......

 

I haven't noticed foam on the dipstick, but I just went out to check the coolant level and it was almost full. I did notice however, that the radiator cap had a bunch of gunk caked on its underside as well. The stuff was like a dark brown/black sticky goo, sort of like uncured silicone caulk. (black silicone caulk, guinness stout... how do you like my similes?) I peeled the stuff out of the cap's spring with a toothpick.

The car seems to drive fine, and all the gauges seem normal. What's up?

Pecos

 

Did you buy the car new?

 

Check oil level too much will churn it up. also use a good quality oil like Castroil not one from seven eleven that sells for 50 cents a quart.

 

No, I bought it from an individual (wholesaler) when it had around 65,000 miles on it. He had bought it at an auction and did not know anything about the previous owner or maintenance schedule. The check engine light was on so I took it to Autozone to have the codes read. They came up P1624, which was something with the diagnostic system and P0713, which was the transmission fluid temperature sensor. I've not done anything about those codes.
There is no visible oil leak (no puddles), but I do burn about 1/2 quart every couple of weeks. That's about all I can tell you.

Pecos

 

Does this car have a crankcase ventilation system that may be defective? Tom

 

At some point someone put radiator stop leak pellets in it
Be on the look out for a leak somewhere
Possibly in between the coolant and oil systems

 

Retired wrench made a good point. Also, how far is the car driven. This time of year short trips can really cause a lot of condensation in the crankcase.(looks a lot worse than it really is) Is the thermostat operating properly. The engine must reach NORMAL operating temperature and remain there long enough to remove condensation thru the PCV system.