Yellow gunk on oil cap.

[Toad]

So I know this has been brought up before on the old org, but i just want to know, what causes this gunk and how do I stop it from forming?

[Mazzzja]

Yeah, I'm curious about that too.
Do you also use longlife oil?

[hannaco]

What is it? That stuff is just condensed water that has mixed with motor oil. This usually only happenes when the weather turns cold.

How did it get there? Water is a by-product of combustion that has gone past the piston rings.

How can I get rid of it? Get the motor hot while driving for a while. About 25 miles of stop-and-go driving or about 60 miles of highway driving. The oil will then get hot enough to drive off the water.

Can it be prevented? With short trips where the motor never gets up to full temp (not just the coolant temp), NO.

Can something be done to make this less of a problem? Use a high quality synthetic oil. I have used Mobil-1, Red Line, Torco, Neo, Esso, and Amsoil with good results. To stop an argument, yes there are other synthetic oils out there that should work. Find one that you like, and use it.

[BlackBug]

Nice hannaco .
My words exactly....

[Toad]

It really takes that long to heat the oil up? damn. And that was with mobil 1.

[rcy]

You could also try replacing the seals in the oil filler cap, and the one in the oil filler neck (the thing you screw the cap onto - just turn it (left or right I can't remember) and it comes off). These seals get brittle over time from the heat and don't seal well. When they don't seal they allow air (cold air in the winter) into the area of the neck/cap and the cold air causes condensation. When the seals crap out, they also allow oil to seep out and dirty up your engine - I had this with the lower seal especially.

Still, getting the oil hot enough to burn off moisture is probably all you need to do.

[Mazzzja]

With the short distances I drive (approx. 12kms to work, one way) I won't be able to get rid of the gunk

[noR]

Originally Posted by Mazzzja

With the short distances I drive (approx. 12kms to work, one way) I won't be able to get rid of the gunk

Maybe not, but you can still clean off the cap & try to clear out the residue.

[rcy]

Just had a closer look at your picture and I can tell you that your seal is toast. See the brown burned look to it (as opposed to the original pukey green colour)? I can almost guarantee that the lower seal in the filler neck will be the same. The new seals I put in are black and were much more flexible than my old seals. Just as an aside, it was cheaper to buy two new oil caps (which include the seal) than it was to buy two seals by themselves...go figure.

Nice Magnecor wires btw - I have the same ones...

[Toad]

so, to remove the filler neck, i have to unhook all those hoses clamped to it and just twist it off like the oil cap to get to the bottom seal.?

thanks for noticeing the magnecor's, those were a really easy install to do. I'm taking baby steps in backyard car maintnence. And the less mechanical it is, the easier it seems.

[rcy]

Originally Posted by Toad

so, to remove the filler neck, i have to unhook all those hoses clamped to it and just twist it off like the oil cap to get to the bottom seal.?

thanks for noticeing the magnecor's, those were a really easy install to do. I'm taking baby steps in backyard car maintnence. And the less mechanical it is, the easier it seems.

IIRC, there's only the one big hose (this is your 'PCV' valve hose - not really a valve per se, but just a hose leading to the intake. Near the intake you'll see a round ring type thing with an electrical connector on it - this is a heater to prevent that end of the hose from freezing in cold weather. But I digress - I don't think I even removed the hose, just twisted the neck off with the hose on.

Anyway, with a new seal, my minor oil seepage where the neck meets the valve cover stopped, and just to give a tighter seal at the CAP end, I left the old green seal in and put the new rubber one on top of the old one.

[HudsonValleyVDub]

Thanks! This thread just saved me a bunch of worry! I just changed my oil and saw that crud under my cap! Scared the crap outta me! I thought I blew a head gasket or something...although the oil itself was normal looking. I'll be replacing my cap...thanks again!

[btb]

It's the winter indicator...

[Evanrude]

Originally Posted by rcy

IIRC, there's only the one big hose (this is your 'PCV' valve hose - not really a valve per se, but just a hose leading to the intake. Near the intake you'll see a round ring type thing with an electrical connector on it - this is a heater to prevent that end of the hose from freezing in cold weather. But I digress - I don't think I even removed the hose, just twisted the neck off with the hose on.

Anyway, with a new seal, my minor oil seepage where the neck meets the valve cover stopped, and just to give a tighter seal at the CAP end, I left the old green seal in and put the new rubber one on top of the old one.

Random question, about what is the approximate price to replace these 2 seals ( or to get a new cap with a seal and then a new seal for the bottom of the neck?) ? Thanks!