What is this black stuff under engine oil cap? [Photo]

[redcivic47]

Hi all, would anyone know what this is and the reason for buildup.

Everytime I fill up I see this dirt inside and it really bugs me.

It is solid and does not wipe if you touch it.

Thankyou

 

[dotty]

Changed your oil in the last twenty years?!

 

[Mark Type R]

Is that not the sign that the head gasket has gone?

 

[redcivic47]

It is maintained well. Has been serviced at Honda through out its life and I personally do oil changes ahead of due times. :S

 

[trickyteg]

Has it ever been flushed with an engine cleaner or Something like that.

 

[Mark Type R]

Is it a gunk type substance or is it dried on?

 

[redcivic47]

The cap should have milky stuff on it, if there is some sort of gasket leak, there is none of that..unless you said it due to some other reason?

 

[redcivic47]

Has it ever been flushed with an engine cleaner or Something like that.

Not that im aware of. Would you recommend that?

Is it a gunk type substance or is it dried on?

It is dried on

 

[trickyteg]

Could always give it a try mate

 

[Stoo.]

It may be carbon.
Just as oil can be burnt off, exhaust gas can leak in to the crank case.

So it could be carbon deposits.