(T) White oil cap

Haven't used my Stilo for 10 days, usually 300 miles plus a week. Checking it over today before using again and my oil cap is white ish, in the very top, like mayonnaise....is this possibly condensation and not the sign of head gasket gone?

possibly just condensation.
clean it out
give it a good long drive or your standard miles and see how it is

If your head gasket had gone you would have bubbling in the expansion tank and water going everywhere if you unscrewed the top with the engine hot.

Surely you get water going everywhere if you unscrew the top when hot anytime?

Searching around this mayonaise is hopefully only condensation, never seen it there before and this xmas period is the longest, 10 days, my car has stood on the drive unused.

Like custard said wipe it clean and give it a good drive round and see if it reappears

Probably worthwhile seeing if there is any oily deposits in the cooling expansion tank. Remove the water filler cap (when engine is cold!), stick your finger in it and wipe round the inside of the tank. If you are getting oily deposits on your finger, then it's possibly your head gasket.

Wiped it clean drove 30 miles in an hour and had a mm size mayonnaise bit in the lid. So not much and very tiny. Will wipe again and repeat. Or is that amount a bad sign?

Coolant looks / feels clean

Cheers

Its only condensation its the cold, time of year dont worry! Ant!

Don't worry. I have also had this issue last winter. Small trips. Car not becoming hot. Stop. Start. Etc. The white grease can also be found down the filler tube, but will disapper after some long hard trips.

Morten.

Not a thing to worry about.
During the damp winter months my filler cap and part of the way down the filler tube has a white film on it. As everyone else says it is just condensation as this part of the engine does not get as hot as the main block. If you still get it during the summer months I would worry a bit.

Cheers everyone, worry over...fingers crossed!

If you're really concerned it might be the headgasket then there is a coolant called 4-life which you can put in which changes colour if there is a gasket problem. You can buy it from Demon Tweeks

As Fiat use metal gaskets most of the time it means that any head gasket leak will take a long time to manifest itself anyway.

jism?