Jump to content

White deposit on oil filler cap

Recommended Posts



I've been looking to purchase an XK8 and viewed one recently.


I unscrewed the Oil filler cap and found a pale white greasy substance on the underside.


The Oil on the dipstick is clean and clear and smells fine.


Suspecting it may signify a head gasket problem, I mentioned this to the seller, a Jag main dealer who said he would ask their head technician.


Took the car for a test drive, had a look again at the filler cap underside and it was completely clear.


Oil pressure was constant and good as was the temperature.


The mechanic arrived, had a look and said he suspected it was simply condensation as the car has barely been used other than ferrying it a short distance to and from the workshop for various jobs.


The car seems well looked after and comes with a two year guarantee on a forty five thousand mile car.


What do members think? Do you think this could be a head gasket problem on the make and would you go ahead with the purchase? Or could it be simply condensation or something else?


Your opinion would be appreciated.



Link to comment
Share on other sites

Hi David,


"Mayonnaise" on the Oil filler cap is something us older drivers have seen before.  I have had it before on a Viva HC which my wife used for short trips.


It is probably condensation build up, but if here is no Oil in the coolant I would not think it too dangerous.  It was in the VIVA for 8 years without a problem.





Link to comment
Share on other sites

Thank you, Jim for your words.


I too am thinking the mechanic probably had it right and as you say, if the dealer is prepared to stand a two years guarantee behind the car, it's probably not something to worry about.


Thank you Jim, I appreciate your taking time to respond.





Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...