I use Shell Helix 5W/30W Professional AG, which according to the Shell online catalogue is the correct oil for the D4FB engine. I keep a look out for when there's a sale so I can get it for 50% off, then,buy 4 or 5 cans.
One thing I have noticed is that the owners handbook states the capacity is 5.3 litre, and yet when I fill it with 5 litres, and change the filter, the oil comes up right up to the Full mark on the dipstick. This is when checking the engine warm and allowing it to drain for 5 minutes on level ground. I've also found that when the car has been serviced at the dealer, the oil level is almost always over the Full mark on the dipstick. In one case, it was so far over that I took it back and insisted that they drain off the excess oil.