What is the gunk collected around the oil filler cap in my Porsche Boxster / Cayman?

It is not uncommon to see yellow-ish creamy emulsion form under the oil filler cap of Boxsters and Caymans, particularly after short journeys during cold weather.

By itself this is usually nothing to worry about; it is just a mixture of oil vapour and condensation that has not had chance to be recycled into the block and sump before the engine was switched off. You can simply wipe it off with a piece of kitchen paper and check the oil level is ok.

However, if you spot a similar emulsion on the dipstick when checking the oil or in the coolant, it could be a sign of head gasket failure and you should book your car in to a Porsche specialist for an inspection.