Subaru Imprezza rec

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Oct 26, 2003
Hi guys, My brother just bought an '02 Imprezza 2.5RS. Manual recomends 5w30 with energy conserving II but also goes on to reccomend various oils such as straight 30 and 40, and 20w50 for very warm or heavy duty conditions. I currently use M1 0w40 in all my familys other cars (2 Volvo turbos, one Audi turbo, and a 24v VR6 Jetta GLI). I would like to use it in the Suby as well just because it is nice to stock only one oil [Smile] Anyway, I would think the 0w40 would be good here in Minneapolis all year. 0 good for the cold winters (car parked outside) and from what I understand M1 0w40 is a bit thin for a 40 so should be just about right for summer. Any comments?
Mobil 1 0w40 is not thin for a 40wt actually, it's basically right in the middle. It's viscosity at 100C is around 14.4cst, and the range for 40wt is 12.5 to 16.3. We have seen evidence that 0w40 M1 thins out to around 12cst after a few thousand miles in a turbo application though. But it's wear numbers still look fine. Subarus in general always show good wear numbers, so you almost can't go wrong no matter what oil you choose. So if you wanted to just stick with M1 0w40 in all your family's vehicles, including this one, go for it.
I had thought of this oil for my WRX, but info that I came across on one of the Subaru chat sites,, indicated that Subaru does not approve of 0W oils. They have not tested their cars with 0W, and therefore would not warrantee the engine in a car that had used 0W oils. Mobil is supplying a 5W-40 Mobil 1 to Subaru dealers. I don't know if this holds for US dealers or not. If the car is still under warrantee, I would stay with the 5W-30 or 10W-30 Mobil 1 or maybe Delvac 1 until the warrantee was up. I also have no doubt that the 0W-40 would work just fine, but there could be warrantee issues. Ed
Yeah, I was just thinking about that. 0w40 is probably a great oil for that motor, but the warentee is something to consider. I doubt there would ever be a claim where oil would come in (what are the chances of having bearing issues, etc while still under warentee?), but it is somewhat disturbing that it could be used against me...anyone have experience in having warentee denied to to oil choice? Thanks Erik
In either case, the dealer would have to *PROVE* that the oil you used caused *DIRECT* damage to the part that they are denying. This is thanks to the M/M act.
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