This yellow goop is what comes out of oil catch cans...

Normal

 

I'd be willing to bet that signs of moisture in the oil is also a function of ethanol in the fuel, which unlike real gas absorbs and holds water.

 

This is why our Prius (and all our gasoline cars) only get 98octane. It has just 5%. Bit pricier but as per my beliefs carbon build up is also less than with 95. Coincidence or not, after some 18months driving with 98 and couple oil changes, oil consumption has got lower. Lets see whether it stay that way

 

I drain the oil catch cans on our 2010 spring and fall. Spring drain is about 50/50 oil/water when I’ve collected it and let it settle. Fall drain is about half as much, and much less water. I’d suspect due to less humid air through summer. So far never see that condition on oil filler cap.

 

?? That's due almost entirely to higher catch can and hose temperature in summer, which leads to less condensation of the water vapor that's plentiful in blowby gas year-round, regardless of ambient humidity level.