Why do our cars get the 'mayonnaise' in the oil filler cap?

[Panthera]

In these colder months I notice and especially this morning quite a bit of thin light brown liquid underneath the oil cap and around the edge of lip where the oil goes in.

Also with that, when is the cut off from normal to head gasket failure?

Cheers

oh, btw, Happy Wednesday everyone :)

[pudding]

Head gaskets don't blow any more, not with these modern MLS gaskets.   They will just seep out of a coolant / oil gallery on a corner somewhere if they do start to leak.

Mayonnaise, mmmmmm, lovely with some strong cheddar and a good quality smoked ham 

Engine mayo is condensation mixed with oil vapour and is totally normal.  It will settle on the coolest part of the engine, which is usually the oil cap and PCV system.  I don't think a lot of people understand that the steam you see from the exhaust when it's cold is the same story inside the engine, it's just steam, not smoke, not a blown gasket, or anything sinister.

This is why engines need a good run, to burn off all that crap that accumulates on short journeys.

[Panthera]

I have been doing a few short journeys of late, which as you mention, could account for the engine mayo. A good run is in order.

Thank you for the reply. 

[unzippy]

The other issue you can get with the car not warming up properly is the exhaust pipes not getting hot enough to evaporate the condensation out of them.

My mum rotted out the exhaust in her new Saxo (back in the day) in just 18 months just doing a short commute.

The condensation mixed with exhaust gasses made a pretty corrosive combo that ate the exhaust system from the inside out.


Obviously we'd like to think VW exhausts are sturdier than Citroen, but still something to think about.

[6waysforward]

The other issue you can get with the car not warming up properly is the exhaust pipes not getting hot enough to evaporate the condensation out of them.

My mum rotted out the exhaust in her new Saxo (back in the day) in just 18 months just doing a short commute.

The condensation mixed with exhaust gasses made a pretty corrosive combo that ate the exhaust system from the inside out.


Obviously we'd like to think VW exhausts are sturdier than Citroen, but still something to think about.

It probably didnt help that the car and exhaust were made of cardboard.
Saxo exhausts always have been bad even from the factory farm.
I know this as i owned a new VTR and had 2 VTS's many moons ago.

[AJP]

So to conclude:

1) Buy a full stainless exhaust.
2) Drive it like you stole it.

Sorted

[lukemk5gti]

 

So to conclude:

1) Buy a full stainless exhaust.
2) Drive it like you stole it.

Sorted

[pudding]

I think the OEM system must be made of stainless as they easily last 10 years!  Or some kind of hybrid made of mild and stainless steels.  Stainless pipes + mild silencer casings. 

Another thing I've seen a lack of heat cause damage to, is radiators.  Not so much intercoolers as they are much sturdier, but the delicate little cooling fins between the rails in water and ac radiators....yeah.....they like to get up to temperature regularly!

My Mum bought a Toyota Corolla brand new in 1993.  It blew up at 53K.  The most reliable car in the world at the time, according to JD Power    The radiator rotted out, it was full of emulsified crap from short journeys, and even the underside of the bonnet had mould and moss growing on it.  It just died on the motorway one day, seized up solid!

It's the same with these 'barn find' cars.  Cars don't like being left standing indefinitely either.  They just rot.  Everything needs to get good airflow through and heat through it.

As AJP says, drive it hard.   If you can't drive it hard on your daily grinds, stay in a lower gear, keep the revs up and get it's blood pumping!