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Discussion Starter #1
During the most recent Polar Vortex I forced myself to venture out into our unheated detached garage to do my weekly fluid checks.
As part of my ritual I always remove the oil filler cap and check its underside. Well there it was, exactly what I was hoping to not see, white cream.
I immediately checked my coolant level and it did seem fractionally lower. But I may have been hysterical, so I have started photographing the coolant level. Time will tell.
This was the first time that I have seen this since my 1985 Mazda RX7 with a Wankel engine. I also remember it from my 1958 Borgward Goliath with an aluminum horizontally opposed 4.
Both of these earlier cars had somewhat of an excuse since both of them had pretty off the wall engines.

My oil filler cap cleared up a little every day as soon as temperatures returned to the normal, just below freezing. After a week and 49 miles the cap was completely clear.

What amazes me is that I don’t remember hearing this phenomenon mentioned on this forum. I would have thought that with the all the oil level checking going on here (for a completely different reason), that at least one person in the Great White North would have encountered it.

Has anyone else noticed white cream under the oil filler cap?
 

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During the most recent Polar Vortex I forced myself to venture out into our unheated detached garage to do my weekly fluid checks.
As part of my ritual I always remove the oil filler cap and check its underside. Well there it was, exactly what I was hoping to not see, white cream.
I immediately checked my coolant level and it did seem fractionally lower. But I may have been hysterical, so I have started photographing the coolant level. Time will tell.
This was the first time that I have seen this since my 1985 Mazda RX7 with a Wankel engine. I also remember it from my 1958 Borgward Goliath with an aluminum horizontally opposed 4.
Both of these earlier cars had somewhat of an excuse since both of them had pretty off the wall engines.

My oil filler cap cleared up a little every day as soon as temperatures returned to the normal, just below freezing. After a week and 49 miles the cap was completely clear.

What amazes me is that I don’t remember hearing this phenomenon mentioned on this forum. I would have thought that with the all the oil level checking going on here (for a completely different reason), that at least one person in the Great White North would have encountered it.

Has anyone else noticed white cream under the oil filler cap?
This isn't a phenomenon or anything worth even thinking twice about. It happens on about every 4cyl engine and occasionally see it on larger engines. But since 4cyl are a single set inline engine it's always seen on them during the winter when it's been wet and cold.

All it is, condensation that forms inside the engine primarily under the valve cover because the engine isn't truly a sealed system. There is a vent between the air box and the valve cover that's completely open minus a mess screen of sorts inside the valve cover.

That condensation because vapor when the engine warms up and then can mix with the oil that is turned to vapor and any splash from the valve train.

Then it simply sticks to the cap and the top of the inside of the valve cover.

The crap will disappear once the temperatures warm up again except you'll have to wipe the crap out of the cap. Won't see it again until next winter. And see it every winter it gets good and cold. Doesn't hurt a thing, any of that crap gets mixed into the oil then drained out at next oil change.

Part of why it's a bad idea to go more than about 5-6000 miles between oil changes if you live where the winter sucks (I live in northwestern Illinois myself).

You can even see a little right after a good set of rain storms if the temperatures are on the cool side.

Don't worry about it, just enjoy your V.

Sent from my SM-G950U using Tapatalk
 

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I previoulsy owned a 2000 Chevrolet S-10 with a four cylinder engine and remember the white residue described by OP. It was in either the oil filler cap or tube opening for the oil dip stick, but it’s been so long, I don’t exactly recall which.
 

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Just as moisture in the air will condense on your windows or glasses it also condenses on the inside of your engine. When the engine is warmed up any water is heated into vapor and the PCV system is pulling fresh air through the crankcase and into the intake manifold so the vapors are removed "drying" the oil. When its very cold out and if you don't do long drives then it may take some time for this to clear out. Most people in the know will tell you to make sure that vehicle gets a longer drive once in awhile. Longer is a vague term and it depends on how cold it is where you are and how many short trips you make on a regular basis as to how long it will take to clear out the crank case. I have read many opinions that its bad to run a car on regular trips less than seven miles as this time it needed to warm up the engine completely. It really is hard to put a definite number on this as there are so many factors involved. We see this in OBD II where the criteria for certain tests varies on how long the car has run but also on the load factor the engine was run under. Sometimes we can make calculations on maintenance based on fuel burned as a engine can run a shorter time but under a heavy load which generates more heat which will clear out the crank case and clean up the oil quicker. This is one of the ways modern automobiles calculate maintenance schedules, monitoring the run time and load values.

This is much too much calculation for the average person so we make it simple. If you are running the car under short trips, that is only a few miles a day, it would be a good idea to take her on a twenty mile (or some other number greater than say ten miles) run at "highway" speeds. This will completely warm up the engine and give the PCV system the time it needs to do its job. Your car's engine will last longer and make you smile more..
 

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Discussion Starter #6
I only mentioned this occurrence because this is the first time that I have seen it in a few decades. I do know what generally causes it and that it is benign, unless it is caused by coolant getting into the oil.
Hence my panic when it appeared that my coolant level had gone down simultaneously, which I will now monitor even more closely.

I have owned in excess of 20 cars, all of which have been inline 4s or 6s with the exception of the RX7 and Goliath. As I mentioned in my OP, none of my other cars except the CRV have had a creamy oil cap. So in over 55 years of driving while living in Pennsylvania and never having a heated garage, I have never before had this occur in any of my other inline engine cars, including my recent 14 years of driving a turbo charged 4 cylinder. Maybe I have just been lucky.

Perhaps the only reason that it had never been mentioned on this forum before is because people don’t tend to open their hoods anymore.
And those that do probably don’t want screw things up by unscrewing anything.
 

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When the polar vortex hit, I suspect everybody's coolant level (in the bottle) dropped a tick more.......a little more contraction.
 

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Checking coolant level while the engine is cold can be very misleading. The coolant really expands and contracts a lot as the temp chances. Look at the level marks on recovery tanks and see how much difference there is between "Hot" and "Cold". Just for fun look at the level on your car when its stone cold. Then after a run when the engine is nice and hot go check it again and see how the level has changed. On most vehicles the coolant will heat its highest temp (and greatest expansion) about ten or fifteen minutes after the engine is shut off. So, the level in the recovery tank will likely not max out until after the car is no longer running.

Expansion tanks were one of the better ideas for cars. You seal up the cooling system which keeps air (with its oxygen) out of the cooling system and that makes your engine and the coolant last much longer. But do check your coolant level at the tank under both cold and hot condition to get a feel for just how much it can vary.
 

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I would also add that IF your vehicle has both a bottle AND a radiator cap (on the radiator), when the motor is COLD occasionally remove the radiator cap and check the coolant level in the radiator. The radiator coolant level should be up at the very top....AGAIN, motor cold. I've seen bottles 1/2 - 3/4 full but the radiator was empty due to a unnoticed coolant leak AND a failed radiator cap (not the bottle cap). Some bottles are pressurized, some are not. The Gen 5 bottle is pressurized.
 
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