Yellow sludge on Oil Dipstick

caomhino · 31-01-2011 4:26pm #1

Hi, I'm driving a 98 Audi A4 1.8 Petrol, 137miles on it. Was checking the oil at the weekend and noticed a yellow type creamy substance on the dipstick. Seems to be above the oil level as it's high up. Anyone have an idea of what causing that ? Head Gasket going ? Car is driving well it has to be said.

dr.fuzzenstein · 31-01-2011 4:31pm

Technical term "mayonnaise".
Can also be caused by cars that are only driven short distances and where the oil is due a change.
This is due to condensation building up and the engine not getting up to temperature for long enough for the water to fully evaporate.
Can also be headgasket failure.

si_guru · 31-01-2011 4:31pm

Have you been doing short journeys in the cold? It could be condensation in the engine as it is not getting warm enough.

Is the water in the expansion tank still there? Yes.. head gasket is okay then.

31-01-2011 4:35pm

If it's the HG the coolant level will have dropped, if not coolant is not mixing with oil

doOh · 31-01-2011 5:07pm

it might go both ways water to oil, oil to water ;P

31-01-2011 5:19pm

Well if the oil is going to the water the mayo won't be on the dipstick

Skuxx · 31-01-2011 6:36pm

My mechanic said to me before that it the mayo is around the oil filler cap then it might not be the headgasket but if its on the dip stick its almost certainly the headgasket!

AzureAuto · 31-01-2011 9:36pm

common enough fault is water leaching into the oil through faulty oil cooler

Nonoperational · 31-01-2011 9:40pm

alan1990 wrote: »

My mechanic said to me before that it the mayo is around the oil filler cap then it might not be the headgasket but if its on the dip stick its almost certainly the headgasket!

Not really the case, if the water level in the expansion tank is not dropping it's not possible to be the hg.

crosstownk · 31-01-2011 10:03pm

Old oil and low oil level coupled with short journeys will cause this.

If this fits the driving conditions then you should really consider changing the oil and oil filter before diagnosing any further.

biko · 31-01-2011 10:04pm

It's hard to tell just from reading but here's my guess:

Take car for a long drive - this should evaporate moisture in the oil.
It can also be caused by overfilling oil, the crankshaft wipping the oil into mayo, so before going for a costly mechanic flush the oil and see if it comes back.
Remove the rubber tube leading to the throttle body, if there's mayo in there I'd guess too much oil rather than HG as the foam gets sucked up and regurgitated.

Yellow sludge on Oil Dipstick

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