Humidity on oil cap

My 912ULS does this always after I perform an oil change so I assume there is moisture in the brand new sealed plastic oil bottles.

I just wipe the oil reservoir cap clean and dont appear to have any further problems.

Regards.....Chook.

Like I said, the condensation is understandable, but it seems to me that the corrosion on the dipstick is not. Shouldn't that part be corrosion resistant?

A lot of talk about short run-ups being a contributing factor, but Ive had several flights in excess of an hour, only to find condensation on the cap the next time I opened it up.

You may boil off all the water during the flight but you will start accumulating some on the taxi in.
Condensation on the relatively cooler Oil tank Cap is expected and unavoidable.
Don't get over concerned about something you can't control.

More important would be to inspect the actual Oil.
I should be relatively clear like it came out of the bottle.
If it looks very milky, you have excess water.

Oil could last for years if it didn't have to suffer from contact with the exhaust gasses.
Consider how often you need to change the Oil in a differential.