ok so please excuse my lack of technical anatomy but hear goes.

Topping up the oil this afternoon (not a lot, just a sort of monthly half a cupfull) I noticed that under the oil filler there's a bit of engine, with a seam down the middle. It's under the carburetor and between the cylinders.

The right (driver's) side of this bit was oily... I don't recall it being like that before. The car isn't loosing lots of oils (as I say I 'top her up' every few weeks) and is isn't smoking/smelling/etc...

Should I ne worries, obviously oil is meant to be in the engine not on it.

It was definitely oil, not petrol, I checked that.

Cheers

Try cleaning it up with some gunk (or similar), you should be able to see any new deposits forming more clearly and may be able to better pinpoint the source.

Might be worth double checking the two 11mm head bolts that secure the oil filler are tight, it's very easy to strip the threads in the ally engine block and therefore not unusual, if this has occured, that the filler will be weeping round its base. maybe remove it and replace the gasket underneath, as this may be leaking.

awesome, thanks guys. I'll take the filter off to make access easier, clean it all up and check the nuts and gasket, then see where I'm at

Filter?

It's meant to do that, stops your engine going rusty.

samfieldhouse I would also check the oil supply pipe between the cylinders. This tube runs behind the cooling fan and corrode over time. You might have a leak there. Alternative check the push rod gaskets. They are getting hard over time and starts to leak.