I've noticed a number of references to a gunky substance that can be found on the inside of the oil filler cap on gas motors, particularly the V-10. For me its a light tan color that wipes right up. I was thinking I got more of it with dino oil than with synthetic, but now I'm not so sure.

A gentleman in another thread is reasonably sure that reflects a coolant leak, or maybe some kind of condensation. Are there any more opinions on this? If you have a gasser, do you have "snot", or not?

 

I havn't noticed it in my F250, but my Dakota just started it when I changed the oil last. It has 120K on the clock. I have heard both that it is a coolant leak or condensation. It gets worse (more of it) as time goes on between oil changes. The oil is always good and never milky. I'm leaning towards condesation, but I check the fill cap and the coolant level every 100 miles. If there is coolant leaking into the oil there is a major problem like a head gasket or something. I've heard that it also might be a winter problem with a lot of short drives. How many miles do you have on your's BareBones?

 

I would not worry about it. Older vehicles had the oil fill cap screwed directly into the valve cover. This meant the cap was always getting hit with oil and it stayed clean looking. Nowadays it seems most vehicles have a 6 inch extension tube between the cap and valve cover. This means no fresh oil hitting the cap to clean it. Now just crank case vapors get to the cap and cause a film buildup.

I have changed the oil on many different vehicles including recent model year Dodges, Fords, and Chevys with V-8 engines and the fill caps all had some gunk built up on them.

 

Well that's good to hear. I've only got 11K miles on mine so its hard to believe there's a coolant leak. But even so, what is it? I have a hard time with the condensation idea because in the winter here in Minnesota the air isn't warm enough to hold a lot of humidity.

 

The white goo is a mixture of water vapor condensation, unburned gasoline vapor, and oil vapor. The cause is blow by when the engine is cold, the piston and rings have not heated up, and expanded to form a tight seal in the jug. And as one poster pointed out, if the area of condensation is not splashed by a sufficient amount of warm oil, it will leave a white, gunky residue.

I had a '72 Super Beatle, and I'd find the wet, white goo in a rubber tube going into the base of the carb; that was a 1600cc air cooled engine. Same thing with my 5.5kw 10hp B&S generator. The generator is air cooled, no liquid, so I know it's condensation and oil vapor mixed together to form the white goo that occasionaly drips out of the crankcase vent tube.

Also had a '76 LTD w/ 351 V8. In the winter I'd collect loads of the stuff in the crankcase vent tube to the base of the carb. I'd clean it out every month or so. I sold the car with 226,000 miles on it, never a problem with antifreeze disapearing into the crankcase nor oil getting into the antifreeze.

My '96 Roadie does the same thing in the winter, and as originally pointed out, the white stuff shows up more w/ dino oil than syn. But the condesation is still there.

We see the condensation dripping out of the weap holes from our mufflers and tailpipes in the winter, no reason to believe it won't collect at the top of extended oil fill tubes and long rubber, crankcase vent tubes.

And as pointed out by an earlier poster, this is noticed during the winter months in all of the above cases I've described.

I'm not saying one wouldn't have a blown head gasket or antifreeze leaking into their crankcase, I would certainly hope not with a new truck. Perhaps with an older truck, keeping an eye on the oil to ensure it hasn't turned to a frothy white, and checking the antifreeze for oil would be a good idea.

Enjoy,
RustyFuryIII

 

It's essentially emulsified oil and water. In other words, mayonnaise, made with different ingredients.

 

And it is more prominent in the winter.

 

That sets my mind at ease. Mine seems to have more of a yellow tint to it.

 

it is condnsation mixed with oil. worry when it shows up on the dip-stick!

 

Thanks Rusty. Your explanation regarding air cooled engines is pretty well bullet proof that the problem doesn't have to be a coolant leak. Thanks to everyone else too. While my V10 runs like a scalded ape, my warranty runs out in one month and I was wondering whether to take it in to preserve the "problem", which now appears just normal. Thanks again.

Nice one Clux - "mayonnaise" is definitely a better and more descriptive term. On the other hand, "snot" probably got more attention!

 

Another vote here for condensation. Often times it is caused by frequent short trips and a simple remedy is to take it for a good 30min+ cruise down the highway so the heat of the engine can cook out the moisture.