I use Mobil 1 10w20 in the Altima and my truck. I also use Mobil 1 or Bosch filters, depending on which one is in stock.
I used to run castrol so sludge didn't happen to me. But I have switched to Mobil 1 full synthetic. Used to run Fram filters but recently me n Bogger have been running different filters and saving them to cut them open to see which is better.
Castrol full synthetic with a fram tough guard filter just bought some motorcraft oil for the car, was like $17 for 5 quarts compared to like $28 for the castrol
Fram filters are made of cardboard... Continue Fram Bashing here http://www.fordfullsize.com/forum/f122/fram-filters-suck-7648/#post273795
When I did my oil change right before the snow hit I put in valvaline high milage full synthetic 10w-30 and Napa gold filter