The dealer I went during warranty used Penzoil 5w50. Since I reached 30k miles I do my own oil changes - using Mobil 1 Synthetic 5w50. As far as the glow plugs are concerned the car has 65k and it is no longer in warranty. The quote I got from the dealer to replace 6 glow plugs was $730. I guess it is too much. I got the glow plugs from the BenzBin for $18 each vs. $23 at FastShop or $36 at the dealer. I already removed the splash shield and top bolts. I was trying to get some confirmation from somebody which did this type of job before regarding the bolts under the manifold.
One more think. If you own a 99 TD the fog lamp wiring will get bad. MBUSA issued a new wiring kit for the fog lamps ($26-28 at the dealer). To replace the old one you will need to cut current wire and join the new wire harness. If your car is in warranty will be done at no cost by the dealer I was told.