Hi; I noticed some creamy foam under the engine oil filler cap when I changed the oil today. I do my own oil changes and do it every 5k and haven't noticed this till now. The car is an '05 Lberty, 3.7L with 65k on it. Car seems to run fine. I am the second owner and purcased it with 56k on it. What could be the cause ?

 

If you do a lot of short trips especially in cold weather, condensation can form in your oil cap in the form of a milky foamy residue. Since you said you just changed ur oil then. Closely monitor your antifreeze level to determine if you are loosing coolant. If the level dropps and you don't have an external leak, then you should consider coolant migrating into your oil.The water pump seal would be a likely culprit at the mileage you have now.

 

thank you very much for the reply. i haven't noticed any decrease in coolant level, or any leaks. will monitor it. thanks again.

 

by the way, it's not a car, it's a jeep.

 

excuuuse me !

 

The memories of my old clunker would prompt me to say there's water (cooling fluid) in the oil, which would point to the head gasket being blown and needing replacing. However, for the new engines I am lost, maybe it's normal?

Do you have more oil in your engine than you put in last time you changed it?

Good luck,
Calin

 

No, I always fill it to the mark. I thought it might be the coolant as well but I don't think so anymore. Vehicle has 73 k on it now and is running fine. Don't really notice much foam anymore. Must have been an anomaly . Don't know....

 

Could have been the cold-ish weather we've been getting in the last few days. Or maybe that's your car's (umm... sorry, Jeep's ) way of asking for a diesel engine?

Calin

 

Did BigRed dig up a year old thread to correct someone on it being a Jeep

It could have been that your oil is not rated for as cold as the weather... picking the right SAE Viscosity rating for your Jeep's weather conditions, if its parked in the shade all afternoon/night and the sun doesn't hit it when you go to fire up in the morning, you better believe that you would need more than a SAE 15W (good to -15C) on those bitter cold days...

if temperatures get too low, the oil will not flow thru the pump at its normal rate and will cause cavitation and give you the bubbles up at the cap. (and potentially do damage if its running too far out of spec, until it warms up)

5W is rated to -25C and would be the better oil for a Jeep during the winter, even if doesn't see the light of day till she pulls up out of the drive way, depends on just how cold it gets down there... If you do short trips in the winter, and dont really let it warm up, and your not up in Yellowknife... then 0W is the ticket since its rated for -30C this is

of course this is all without the aid of an engine block heater, since that keeps it warm, so the oil doesn't get down to those extreme temps.

 

The bottom of my oil cap also looks like a milky sludge cake. I clean it at every oil change with varsol.
The consensus is that short trips and cool wet damp weather add to the milky way caking of the filler cap.
On my 04, the PCV is located on side of filler tube, and it should be checked and cleaned annually, and replaced if it is gunked too.