White Antifreeze Slime in Oil Fil Cap

[meddler]

In the process of doing an oil change today on my 98 Legacy Outback (2.5, MT - 177,000 miles), I noticed a white slime in my oil fill cap and down the fill neck. - indicating that antifreeze is mixing with the oil. Could this be anything other than a head gasket? I'd think that if that were the case I'd have overheating issues and bubbles in my antifreeze overflow tank as well. Also, the oil i drained out looked normal, it was just around the filler cap.

[aircraft engineer]

In the process of doing an oil change today on my 98 Legacy Outback (2.5, MT - 177,000 miles), I noticed a white slime in my oil fill cap and down the fill neck. - indicating that antifreeze is mixing with the oil. Could this be anything other than a head gasket? I'd think that if that were the case I'd have overheating issues and bubbles in my antifreeze overflow tank as well. Also, the oil i drained out looked normal, it was just around the filler cap.

 

not likely - the only way the oil and coolant system get "mixed" is either "dump antifreeze in the oil" (which is sort of "too stupid to think about") or the coolant is leaking into the oil - probably HG (but not ABSOLUTELY - just the most likely suspect) It still will require a tear down to figure out exactly what failed

 

not what you wanted to hear, but you thought about it anyway Remember - if you have a failure - it's better to have the oil into the coolant rather than coolant into the oil. Coolant running around in the oil system can ruin things "quickly" - you would be better off to park it and fix it rather than drive it

[OB99W]

In the process of doing an oil change today on my 98 Legacy Outback (2.5, MT - 177,000 miles), I noticed a white slime in my oil fill cap and down the fill neck. - indicating that antifreeze is mixing with the oil. [...]

The "slime" is an oil/water emulsion, often similar to mayonnaise in appearance and consistency. This will sometimes form in perfectly normal engines under certain operating conditions (in particular, short trips in cold weather, leading to condensation). Now that the temperatures are coming up a bit, you could clean up the oil cap and pipe and see if the emulsion returns.

 

Your engine, given it's mileage, may have a bit of excessive blow-by. It also could be that the PCV needs attention. Check or replace the valve, and make sure the hoses aren't plugged.

 

Although it's possible that the emulsion is due to coolant, I wouldn't jump to that conclusion even if the antifreeze level appears to be going down. It's possible that there's just a small external leak someplace. Check hoses, consider that the water pump may be "weeping" a bit, etc. You can always cross the "bad HG" bridge when you get to it.

 

Good luck.

[nipper]

When was the last time you changed your PCV valve?

 

 

nipper

[frag]

The "slime" is an oil/water emulsion, often similar to mayonnaise in appearance and consistency. This will sometimes form in perfectly normal engines under certain operating conditions (in particular, short trips in cold weather, leading to condensation). Now that the temperatures are coming up a bit, you could clean up the oil cap and pipe and see if the emulsion returns.

 

Your engine, given it's mileage, may have a bit of excessive blow-by. It also could be that the PCV needs attention. Check or replace the valve, and make sure the hoses aren't plugged.

 

Although it's possible that the emulsion is due to coolant, I wouldn't jump to that conclusion even if the antifreeze level appears to be going down. It's possible that there's just a small external leak someplace. Check hoses, consider that the water pump may be "weeping" a bit, etc. You can always cross the "bad HG" bridge when you get to it.

 

Good luck.

 

+1 on that.

[meddler]

I crawled under the car yesterday and noticed a small antifreeze leak around where the lower radiator hose connects to the thermostat housing - that would explain the decreasing antifreeze levels. The PCV valve was new about 10 months ago, so that's probably ruled out. However, my daily driving consists of two trips of about 10 miles. Here in Maine, it's been cold and damp and I haven't been letting the car warm up too much - I could see this creating condensation especially because I drive short distances. I'm just going to keep an eye on it and see if/how quickly the slime reforms. Thank you everyone for your quick and informative responses.

[mbshop]

just as you last stated the oil/engine is not heating up enough nor long enough to burn off the condensation. if you cannot burn this off regularly then i suggest that you change yer oil more often. this stuff produces hyd acid that can eat out yer eng especially the bearings. as it stands yer eng is just getting heated up. try to go on longer trips or yer back to the more frequent oil changes. there are tests to see if you have a bad hg but i doubt it.

 

george