Goop in oil fill cap

xavierny25

Member
Mar 16, 2014
6,323
Staten Island, N.Y
I've never seen the cap on my Voy look like that. I also use mobile 1 exclusively. It might be time to have your oil tested.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
I just changed the oil. I might have thought an internal coolant leak that is emulsifying the oil, but the oil I drained out looked fine. Jet black, no foam.
 

mrrsm

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Oct 22, 2015
7,639
Tampa Bay Area
Not knowing "whether the weather" where you are is Extremely Cold right now... In the Best Case Scenario...The Usual Suspect for this situation is caused when one of the by-products of normal engine combustion (Water Vapor) that passes the Piston Rings as Steam and winds up mixing with the Engine Oil. But once the Engine is turned off that 'oily water steam' separates from the Motor Oil and condenses in the upper Valve Cover Chamber which has a long thin metal plate running the length of the cover...and forms a protected air chamber located at its highest point...and that becomes The Oil Filler Neck and Cap. That frothy mixture can condense inside of the Oil Filler Cap very quickly if the outside air temperatures is extremely cold.

There is ONE OTHER THING that can cause "Frothy Oil" and that is by Over-Filling your Crankcase (with NO Baffle Plate to prevent this from happening) enough to have the Rotating Crankshaft Throws make direct contact with the Oil in the Pan and literally...Whip the Motor Oil Into a FROTHY MERINGUE! Your Engine Gerotor Oil Pump can only pump a solid stream of incompressible Liquid Motor Oil... and will be incapable of pumping enough Oil Pressure when it is mixed like this... with Compressible Air.

In the Worst Case Scenario ...it is Engine Coolant-Anti-Freeze mixing with Motor Oil. In most cases...the result of a Head Gasket Failure. This problem can occur when an engine with a Long Aluminum Head is started with rapidly elevated RPM during periods of extreme cold and the sudden temperature changes can presage warping the head enough to cause a Head Gasket Failure. Check your Engine Oil Dipstick for the presence of this same "Brown Pudding". If you are lucky and find none... Clean the Oil Cap... Check your Oil Level in case it is TOO HIGH and GOOPY BROWN in Color ....but if it appears normal... then everything is probably Okay.

However... if you find this dreadful stuff on the end of the Dipstick.... Do Not Start The Engine as this substance has NO lubricating qualities and will rapidly have dissolved the Engine Bearings due to its High Acidity via Electrolytic Corrosion while sitting there... and until that stuff is drained out and flushed and New Mobil1 and New Oil Filter is introduced... you run the risk of seizing the engine shortly after start-up. I am very sorry to have to tell you that if this becomes the case... this one is bad enough to require a tow to a competent auto repair shop... and an absurd amount of money for the Head Gasket Repair...which may include replacing the Engine Head:

 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I haven't seen this in recent memory but an old mechanic once told me that's water vapour condensation. You might have a bit of condensation in your engine and it will evaporate when the engine gets hot and condensate at the highest and coolest spot. Mostly affects winter areas and short drives. So technically, you do have a little water in your oil but it's so little, it's harmless and doesn't stay in the lubrication system. Just clean out the cap once in a while. It might help if you drive the truck till it gets really warmed up. Another thing to check is your thermostat.
 
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Sparky

Member
Dec 4, 2011
12,927
If the oil you drained looks fine, then I'd chalk it up to really cold temps causing condensation. I've had that before on my oil fill cap a few times, but not in the oil itself. Gross looking yes.

You should see the contents of my oil catch can in the winter. Lovely.
 
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Bow_Tied

Member
Dec 21, 2014
453
London, ON
Does your rig do a lot of short trips in the cold climate and is the engine getting up to temp? I have seen this before but never that bad. How long does it take for that to accumulate?
 
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bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
I'm in Wisconsin. Other than the three days of 40's we had last week, it's been damn cold for about a month. The TB is my wife's DD so it does do quite a few short trips. She drives 3-4 miles each way to work each day, but it does do quite a few long trips too.

I can't really say how long it takes to accumulate. I'll have to admit, the oil change I did today was quite a bit overdue (7 months and 8,300 miles, but before the oil life monitor said it was time for a change). I'll have to keep an eye on it. I've seen this goop before, but I've never correlated it to cold weather. It's not there all the time. Maybe it's only showing up in the winter. It did throw a P0014 code twice about a week ago. I cleared it with my Torque app and it didn't come back. From searching this forum, sounds like those can come from dirty oil (which is why I got off my a** and did the oil change despite the fact that it was 5 degrees out).

I'll report if it keeps coming back while it's cold or if it goes away if it warms up (if it ever warms up).

Just put new tires on the TB so I'm signed up with this thing for another five years!
 

Bow_Tied

Member
Dec 21, 2014
453
London, ON
Buy her a remote starter and have her use it before short trips on cold days. It will extend the life of the exhaust too. If it gets really cold like -30 (-22 in the old system) then consider regularly using a block heater and/or a cold front for the grille.
 

Kelly@PCMofNC

Member
Mar 16, 2013
184
It's normal. Unless you drain the oil and it looks like that, then it's perfectly normal to see that under the cap.
 

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