Mobil 1 0w-40 - 6850 Miles - 2011 Subaru WRX

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Jul 21, 2011
This UOA was after the 3rd run of Mobil 1 0w-40 and Fram Ultra oil filters.

The 1st UOA listed was Pennzoil Ultra 5w-30 with Bosch Premium oil filter.
The 2nd UOA listed was Rotella T6 5w-40 with Bosch Distance Plus oil filter.

The driving continues to be approximately 85% Highway / 15% City.
There was nothing unusual or different about the driving than normal despite the higher Iron noted by Blackstone.

I'd be more worried about alum or copper in that engine both of which are good.

for whatever reason M1 seems to track with slightly higher iron in UOA, which doesnt = wear

rts 5w40 is a favorite in those engines.
M1 in a Subaru! Yikes!

Most like the reported results are related to the LL drain nature of the reportedly excellent ACEA 0w40 oil. If you went an intended - or at least more rational - 10K OCI, M1 overall ablation performance would likely surpass the RT6 which I'm guessing wouldn't make it to 10K in your service.

Any pressurized subie guys try and run EDGE gold bottle synthetic 10w30? This stuff Seemed robust when I tried it in the Honda - Too robust for a non boosted 1.5L actually.
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weaselgnome - As I reported in another Thread, it is always a good idea to look at the uptake rate (per km or mile) when comparing results. The actual distance is not shown for the Universal Averages so the Unit/Location Averages are meaningful for you - always remember that we are comparing uptake rates on Parts Per Million (PPM) - very very small amounts!

The M1 0W-40 lubricant in this application did very well indeed
Nice uoa and not much more to say (hey, I made a rhyme).


ARCO, folks rarely seem to use 10W-30 in these engines even though it's on the temp chart in all pre-2011 WRX manuals. I ran M1 HM 10W-30 one oci, but no uoa. edhackett has some good RT5 uoa's from his Legacy turbo posted here.


So much for the idea that M1 isn't compatible with subaru's,because this uoa looks great.
Way too short of an interval though. The tbn didn't even get half depleted,which I find impressive considering the reputation that Subaru engines have for thrashing the engine oil.
This oil could potentially run 10000 miles under these conditions.
So what's your plan? Looks like rotella if running a 6000 mile interval or M1 fir 10000.
What's the cost difference between both flavours and is it more cost effective to run rotella for a shorter interval or M1 for longer? Figure out the cost per mile,including the cost of the uoa so you get an accurate assessment.
I think I'd go with M1 and a longer interval simply because M1 0w-40 is one of the best oils on earth,and less wrenching.
I don't think there's more than 5 bucks difference between the 2,which makes the M1 0w-40 a better value based on it costing less per mile.
In my area, the Mobil is approximately $3 cheaper for my oil change. Given the ability to go more miles, Mobil is more cost effective overall. With these results, I will be getting another UOA after approximately 8500 miles and go from there. With UOAs I've seen for these engines and my own, I haven't been comfortable even going the Subaru recommended 7500 mile intervals until now. However, with Mobil, I will be comfortably extending beyond this for subsequent changes and UOAs.
Originally Posted By: weaselgnome
However, with Mobil, I will be comfortably extending beyond this for subsequent changes and UOAs.

That's getting your moneys worth with the UOA. I'd run it to 10k and take a sample. I'd bet that the TBN wont be depleted and you could run it year round. I ran 40 weight religiously in my boxers (Version VI STI). Never anything lighter. I did 10w40 and 15w40 but had I known 0w40 was so good in those days I would have run it no problem.
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