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[Phil.d]

Can anyone please tell me another reason why I'm getting this gunge in the filller neck. The facts so far are no oil in expansion tank and no water in oil .  Head gaskets were  done last year , its not bcause I'm only doing short runs either . Been told you get a little in when its cooler weather but its moer than that . I'm relying on the few die hard omega members out there know whats going on.

Thanks in advance.

[tunnie]

Its called 'mayo' and don't worry its normal, its caused by short runs, engine not getting hot enough and condensation forming underneath oil filler cap. Some oils are worse than others, Castrol is very bad for Mayo, GM's own 10/40 Semi is best all rounder and amazing value on trade.

I'd give it an oil change with 10/40 and give it a long blast 

[Phil.d]

I had the car serviced before  xmas and put some slick 50 in as well. Had a good run last week upto Sheifield and leeds so it does have longish journeys. I've asked wether the breather system might be partailly bnocked but not really got an answer.

[al brown]

Hi, Mine seems to gather mayo after a couple of short runs even after a long run has cleared it. TBH never seen much difference between oils but then as its a know issue with migs I never worried much as it clears itself after a good run, so I only check/clean the inside of the filler cap now and then
Al

[belldarr]

I have noticed the same on my 3.2 and it is a bit of a worry but it seems to be the case that these engines seem to suffer from it when the weather is colder.

Darren 

[johnnybbad]

Its been mentioned on here that due to the filler neck being located away from the engine, that it does tend to gunk up a bit

[al brown]

As long as there is no oil in the header or mayo on the dipstick you will be fine.
Al

[bri cox]

i have been told by ex vauxhall mechanic that in winter the mayo is worse as the engine  cools downs it sucks in the cold damp air throw the breather pipe and condensates at the highest point. the oil filler cap and neck and thats its nothing to worry about as long as you service your car properly which was a relief to me as i thought it was going to cost the earth to fix 

[manny]

Just remove the filler neck and put yellow oil cap directly on rocker cover. This cures it. I put mine back on to do oil changes and top ups. There is a plastic tab you lift on bottom of filler neck ,lift it up and turn filler neck anti clock wise. No more mayo.

[Entwood]

It is really very simple ..... the engine gets hot, so the oil gets hot, so any moisture in the oil tank (from the atmosphere) gets hot and evaporates. This hot moist air/oil vapour mix rises to the highest point .. the top of the filler neck where it gets trapped, the filler neck is in the airflow caused by both forward movement of the car, and the spinning of the fans .. so the neck gets, relatively, cold .... the hot moist oil/water mix condenses on the neck  as an emulsion .. thats what you see ...

If you do long journeys and work the engine hard, the whole filler neck will, eventually, heat up and the emulsion evaporates. .. it then passes through the breather system.. where it may well condense again ... if the breathers get blocked by this, then the emulsion is trapped in the sump....

When you reach the end of your journey you switch off and the engine cools, as it does the air inside the sump contracts and air enters fromt he atmosphere to compensate. This air may well contain more moisture .... especially in the winter .. so starting the whole cycle again.

Some oils give of more vapour than others, so causing more emulsion.

It is common and nothing to worry about, regular oil changes with Vx semi 10/40W, regular breather cleaning, and the occasional longer trip will keep the "gunge" down to a minimum ..

HTH

[Broomies Mate]

This may sound like a really stupid question, but..........

Should I worry that I NEVER get any sign of Mayo on the filler cap?

Most of my journeys over the last couple of months have been very short, temp gauge not really moving at all in fact.

I'm concerned because everything is right 

[david_omega]

i like car auctions, see the mayo and people say oh my god the head is nackered, then i sometimes get a cheap one! it has happened, but not that often!

[Dimsum]

Quite a common thing on my last 5 series too... A good blast always got rid of it!   

[duggs]

Surely its better to keep the filler neck on...Least that way you know where the "mayo" is forming or are we suggesting that without it the oil is constantly getting hot enough to prevent the stuff from forming in the first place.

[Phil.d]

Thanks for the response everyone , you would have thought vx would have come up with a fix for this. I'm looking at a friends 2.6 later , he's just got it so I'll have a nosey at his.