not sure if any 1 has ever mentioned this before but here goes,a week has gone by from not using my sierra cosworth,i was replacing the hoses what go to my baileys oil breather bottle and noticed there was white mayonase gunk inside .me thinking the worst it was headgasket at fault i then was told it is down to the very cold weather we have had up here and it was condensation what has mixed with the oil,so after a quick oil change and flushed the tank.hey presto all gone until i next neglet using the car,lol,so keep a eye on this as it might affect your oil.

 

similar thing happens on the mk4 golf gti,

its condensation, mostly on cars used on short journeys, the car doesnt get hot enough to clear the moisture

 

Can also be made worse with cheap oil.
tabetha