I recently bought a 2007 Saab 9-3 2.0T 6-speed with 106k as a daily driver. It has the high output turbo but has not been modified nor will it be modified. The recommended oil is stated as Saab 0w-30 or Mobil 1 0w-40. The oils I'm considering are Shell Rotella T6 5w-40, German Castrol 0w-30, Shell Ultra 5w-40, or defaulting to the overpriced Mobil 1 0w-40. Now let me mention that I have spent several hours on BITOG and other forums researching all of the oils and I still don't feel like I have a satisfactory answer. There is sooo much disinformation out there. Anyway, if you're about to respond and say that this topic has been discussed ad nauseum (I recognize that) or tell me the owners manual says Mobil 1 "nuff said" or tell me that you think xx oil blew your engine, well, please just don't pollute the thread with those types of responses. As far as I can tell all of the oils I mentioned will be fine, but I'd like ideal. The Rotella has alot of support, especially from subaru owners and truck drivers. It's the easiest to find and the cheapest. I'm not too concerned with the fact that its a diesel oil; it could be good to clean the engine with its robust additive package anyway. I am concerned about the 5w weight when the owners manual specifically calls for 0W and I live in MA which has pretty cold winters. From what I've read, I guess the M1 is the thinnest at startup, followed by GC, and I'm assuming the PU and Rotella would be the thickest- but I don't know how big of a difference it would be and its not like I'm ever starting my car in anything less than 0*F. Then on the operating weight. I understand that M1 is a very light 40wt that supposedly shears down rather quickly to a 30wt. GC is a very heavy 30wt that doesn't shear as much and may actually be thicker than the M1 at operating temperatures. I couldn't find much info on where the PU and Rotella would fall here. Alot of people say the Rotella is pretty thick, then I read others claiming it shears down easily. Ive read from people that put the Rotella in a 4 cylinder car say that the throttle feels a little bogged down and the MPGs are slightly worse. I certainly don't want to bog my engine down and i understand you want to go heavy as necessary, light as possible. Then again I have a turbo which might benefit from that heavier oil. As far as base oils go, although I know I shouldnt be too concerned with this, The Castrol is a group IV, The Mobil is a III+?? and the Rotella and PU are a very good group III. Again with the turbo, would a group IV hold up better? So anyway, my head is littered with hearsay and I really don't know which way to go here. I was thinking GC but people say its an old formulation, some people complain about startup noise, I had a mediocre experience with it in a 99 G20 a long time ago, and I wonder if the additive pkg will be enough to clean the engine. Then I thought Rotella but got concerned about if its going to be too heavy, maybe I could run it with some MMO? I was going to buy a case of PU on amazon for $42.50, but theres not much info on it, I fear it might be too heavy, and the reviews I've found on it are not too impressed with it. Mobil 1 would be the easiest if it wasnt so hard to find and expensive (Local walmart does not have it and there are no deals on it right now) and its not a perfect end-all oil anyway. I read one thread where a guy recommends GC, Rotella, PU in the order for a Saab. And another thread where a guy says in a world with Mobil 1 0w-40 why would anyone use Rotella in a car. So, great BITOG, what oil should I choose?? And if I made any incorrect assertions please feel free to correct me.