Rotella 5w40 Mobil 1 0w40 GC 0w-30 turbo 4 cyl

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Feb 21, 2013
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.
The SN version of M1 0w-40 doesn't shear like its predecessor. So it would be heavier at operating temp, but still thinner than GC at lower temps due to its higher VI.

I believe it is the best choice for this application.
I'll give a thumbs up for any of those oils, but my personal choice would be the T6. It's actually not a diesel oil, it's an HDEO (heavy duty engine oil) designed for "high stress" applications and it carries API certification for use in gasoline engines. I like it because it's, as you mentioned, cheap and easy to find. On top of that, it cleans quite well in my experience.

Honestly, go with whichever of those oils you can get the cheapest when it comes time for your oil change.
Use the one that's readily available to you. You'll see M1 and PU in my turbo swedes...but GC would be a great choice and I've used T 6 too...
I tend to lean more toward the M1 because it has so many factory approvals and performs well in high performance applications. But the GC is no slouch either! If it were me I would have to try them both and get uoas to make the decision for me.

You seem very informed for a new member
There is no difference in cold start wear factors between a 5W and an 0W until you get below minus 25C. The 0W will give your battery and starter motor a slightly easier time BUT the wider the hot and cold spread the more VI additives are required so the faster the oil might shear to a lower grade.
It probably will make no difference which one of the oils you list is used, so I would just pick the cheapest.
Pennzoil Ultra or Rotella T6 in summer
Mobil 1 0w-40 in winter
OR GC 0w-30 all year.

Pennzoil Ultra has a slightly lower VI but is more shear resistant than T6 (assuming T6 HTHS is 4.1) PU is also slightly thinner at low temps due to its low KV100
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As this is not a highly stressed engine(105 hp/ltr), I would go with whichever of those oils is most accessible/cheapest. They are all very good oils that wont really be tested in this application so go with whatever is on sale or makes you sleep best at night.

I'm partial to M1 so I'd say go with the 0w-40.
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M1 is on sale quite often at the Auto stores (AAP,AZ etc) I would go with that as your best bet for all year use. It is an outstanding oil. GC is good and on sale quite often too...


Wow alot of thoughtful responses. Looks like I came to the right place.

Most of the votes are for M1 with GC as a good alternative and everyone agrees that any of the oils would be fine.

The newest version of M1 does not shear down to a 30wt. There's no difference between 5W and 0W cold starts unless it gets real cold and the wider the range between the numbers, the more VI additives are used which can result in a higher propensity to shear. PU is a little thinner and has a slightly lower VI than T6 but will shear less. Do I have that all right? I know I I want a high VI, I don't know what HTHS or KV100 is.

AZ has GC on sale 5 qts plus a filter for $34. I already bought some Saab filters so I'd hope I could get them to sub an extra quart (I need 6) for the filter.

With a coupon code I can get 2 gallons (only need 1.5 but could save it for next change) of Rotella with a bottle of MMO as a filler item for about $42 - $31.50 for what I'll use.

At PepBoys, I saw a coupon for $7 M1's so that would be $42. Here's the coupon if anyone wants it:

I also found an old 5qt container of M1 0w-20 and a quart of M1 0w-40 I have. I'd be crazy to use that right? Could I just use the old 0w-40 and buy 5 new ones? The bottle I have is probably 2.5 - 5 years old.

Thanks for all the replies and Im glad to be a member here.
Personally, as most say - it is all about what is priced best. All of the oils would do fine. I find GC almost impossible to find, but I also do not search around much. WM always has Rotella pretty cheap, as well as Pennz and M1. Keep an eye out for the Pep Boys M1 deal with M1 filter they run every few months, that is probably the best bang for the buck since a very good filter comes and you can pick any M1 you like, you can even mix and match their weights/blends. I would lean more towards M1 or Rotella only due to price and accessibility near me, and that is the only reason I would even lean. may want to remove the oil pan and check the oil pump intake screen for debris. Sadly,Saab engines were notorious for baking the engine oil and sludging. Saab (RIP) had some service bulletins, extended engine warranties, PVC updates and so forth. It may be the catalytic converter and exhaust piping is too close to the engine oil sump and cooks the oil pan..who knows?

Someone out there even makes a Saab oil pan with a removable inspection plate to clean the oil pump gets plugged up as the intake screen is a very fine weave..starves the engine of oil and destroys the rod bearing,main bearings and cams. Many engines have been me.

Most Saab shops are very familiar with these issues and can help.

I would have the pan off and everything inspected/cleaned prior to selecting an engine oil. Once done, I would use Rotella T6 and change it every 3000/4000 miles.
In the interest of getting it done I stopped at autozone this afternoon to pick up the GC with the special theyre running but the guy wouldnt let me sub out the filter for an extra quart. He said 'tell you what I can do, I'll give you the deal without the filter but you'll still have to buy the extra quart' 'So you mean you can charge me the same but I dont get the filter?' Yeah. So I went across the street to advance auto and bought 6 quarts of M1 at full price. Im sure M1 will run a deal next month so I'll hold onto the receipt and match up the price then. I like the Rotella option but I don't see how its that good of a deal. $28/gallon (about $21 if I get all fancy with the coupon codes) and I have to buy 2 of them, GC was $34 and I bet M1 will be right around there when the spring sales start next month.

The oil pan bolt was on there ridiculously tight, probably impact wrenched, and it was overfilled by close to a quart. I spent so much time trying to get that bolt off that I didnt even do the oil change - I just drained out the extra quart, and put some MMO in to start the cleaning process. I might finish the job tomorrow or maybe Ill leave the MMO in there for a week.

DB- I think the sludge you're referring to is on the older models. The 03+ models supposedly dont have the issue. I might drop the pan when the weather warms up though just to be meticulous. Is there any reason you specifically recommend the Rotella for a Saab?

I've noticed quite alot of discussion about SM vs SN Mobil 1. The bottles I bought say API SN,SM,SL. So would they be considered SN?
If your Mass winters are like Quebec winters, the GC is too heavy for the December-march stretch IMO, OK for the rest of the year.

I have yet to see any real-world demonstrations in which anything flows better than M1 0W40 in the minus -20's & -30's. The Petro Canada Synthetic 0w30 and Duron 0W30 would be next closest ... but not sure about the other end of the thermal scale - Petro Canada was busted on VOA's a couple of times for lying about additive levels & HTHS although that was several years ago. But those Russian guys on Youtube who do the outdoor -30 tests in Siberia seem to think it rocks in the cold.
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