I have a 1998 A4 2.8 87000 miles. the car runs great but it has been the last two oil changes that i been noticing white sludge build up in the oil fill cap and the dip stick. can anyone explain. I'v owned this vehical 8yrs know and i purchased it with 26000mi and never had that problem. i change the oil every 3000mi.

 

Your getting water or water vapor in the crankcase. Check for cracked breather hoses. Especially the one that goes from the right bank to the left bank.