Mobil One 0W-40, 2000 Audi S4

[FixedWing]

Latest sample 5527 is Mobil One 0W-40. Sample Nos. 549 and 927 were also Mobil One 0W-40. Sample 4008 was Castrol Syntec 0W-30 (German Castrol).

My reaction: generally good. I like that the fuel contamination is staying at a reasonable level. But M1 0W-40 sure doesn't like staying at its viscosity. In the end, there is almost no difference between the viscocity of M1 and GC.

I now have GC 0W-30 in my car so it will be interesting to see what the wear numbers do with that.

Stephen

 

[FixedWing]

quote:

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Originally posted by Eiron:
Yeah, turbos tend to do that to oil. There's another S4 (2001) UOA on here with Castrol 5W-40 that thinned out quite a bit, but the M1 0W-40 UOA for my non-turbo Saab 900 showed its vis has held well so far (12k miles).

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The car does seem pretty hard on oils. I feel very comfortable with the 5000 change interval and have no desire now to try to stretch it.

I wish I knew how to interpret the lab's new Oxidation test. According to the lab:

quote:

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Measures the overall breakdown of the lubricant due to aging, operating conditions, or internal overheating. Test results are reported on an infrared absorption scale ranging from 1 to 99.

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Wear Analysis Report Legend

But I have no idea what 25 and 31 actually mean.

Stephen

 

[y_p_w]

quote:

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Originally posted by FixedWing:
My reaction: generally good. I like that the fuel contamination is staying at a reasonable level. But M1 0W-40 sure doesn't like staying at its viscosity. In the end, there is almost no difference between the viscocity of M1 and GC.

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That's supposedly the M.O. of Mobil 1 0W-40. It's on the thin end of 40, the VI improvers break down quickly to make it in the 30 weight range, and oxidative thickening will eventually bring it back to 40 weight.

Mobil has tailored the formula precisely for the ACEA sequence tests. It'll meet the A3 extended drain test because the only measurement points are at the beginning and end of the test. The viscosity breakdown increases the fuel economy over the length of the fuel savings sequence test. There was a time when Mobil 1 0W-40 actually met the API SL "Energy Conserving" standard.

If you actually went with the recommended drain period, I think you'd find that the M1 0W-40 would likely have thickened back into the 40 weight range. Your drain period seems to be well under any VW/Audi recommended period.

I'm using M1 5W-30 in my 2004 WRX. I've found that viscosity has been maintained fairly well over 3-5K drain periods.

 

[Eiron]

Yeah, turbos tend to do that to oil. There's another S4 (2001) UOA on here with Castrol 5W-40 that thinned out quite a bit, but the M1 0W-40 UOA for my non-turbo Saab 900 showed its vis has held well so far (12k miles).

 

[FixedWing]

quote:

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Originally posted by y_p_w:
I'm using M1 5W-30 in my 2004 WRX. I've found that viscosity has been maintained fairly well over 3-5K drain periods.

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I think I would prefer to use GC 0W-30 rather than M1 5W-30 in order to get the lower cold viscocity. For now, I will continue to use M1 0W-40 in the summers since it is at least slightly thicker than GC even after it has thinned out. But I do wish that it would actually stay in its viscocity band.

Stephen

 

[williar]

I've used botm M1 0w40 & GC in my allroad 2.7t. Both seem to do well for 10,000 mile OCIs, but I prefer the GC.

 

[FixedWing]

quote:

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Originally posted by williar:
I've used botm M1 0w40 & GC in my allroad 2.7t. Both seem to do well for 10,000 mile OCIs, but I prefer the GC.

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I think a lot of it is down to usage and driving style. I think 10,000 miles can work for many but in my own case, that would be unwise given the fuel dilution.

Stephen

 

[zoomzoom]

Hm your chromium and fe jumped quite a bit..iron is probably due to cold weather.

Chromium is probably from rings?

I think GC is better for our cars!

 

[FixedWing]

quote:

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Originally posted by zoomzoom:
Hm your chromium and fe jumped quite a bit..iron is probably due to cold weather.

Chromium is probably from rings?

I think GC is better for our cars!

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Let's put it all in perspective, these numbers are all quite reasonable. I don't think small changes at this level are significant.

I do like GC. It is in the car now. My intent is to use it during the winter months.

Stephen