Castrol GC 0w-30 in 04 Dodge SRT4

[Idrinkmotoroil]

Received my latest sample, this was running GC 0w-30 in a Dodge SRT4, turbocharged 2.4 L engine, for 5900 kms, which is just over 3,500 miles I believe. I typically run OCI's between 3,000 and 5,000 miles to keep the warranty guys happy.
This is a very simple elemental analysis, nothing fancy for $14 cdn, CAT labs. SOS Fluid Analysis.

Iron - 8
Aluminum - 1
Copper - 1
Lead - 0
Moly - 97
Zinc - 687
Silicon - 11
Viscosity - 10.4 cst

Wear metals looked good, very similar to runs I have on Mobil1 10w-30 and Redline 10w-30, I wouldn't say any better or any worse. But I was very surprised on the end viscosity, it has sheared down quite a bit. My Mobil1 sample had visc. of 10.1 after 5500 kms., and my Redline 10w-30 sample had a viscosity of 10.8 after 7700 kms. It appears that the Castrol GC 0w-30 has sheared down a fair bit considering it starts at a very thick 30 weight , approaching 13 cst ?.

The Moly in the GC sample is left over from my last Redline run, so it probably benefitted a bit from having a decent dose of Moly in it from the previous sample. I liked the fact that the Castrol GC had less oil consumption than the other oils I've run, other than that nothing out of the ordinary. There were other metals tested by lots of zeros in the analysis so I left them out. I believe this engine uses aluminum bearings, perhaps combined with copper ? (not sure) so there is no lead detected in case anyone
notices the low lead reading. Either way the bearings are being well protected particularly on a turbo application such as this, which runs up to 19 psi boost.

Joey

 

[nobadges]

CAT Labs. Is that Caterpiller?

There's Toromont CAT here in town. I didn't realize they did analysis. I will give them a call.

 

[Triple_Se7en]

Maybe the shearing is a sign of aging oil. Some folks here have GC that's four years old. What was the date on the GC jug-bottom? Maybe it thins with some turbos?... I dunno! Is this how CAT Labs sends their UOAs -- only an 8-item list?

 

[jkhawaii]

hmm the redline dose not shear at all. redlines spec sheet says
10.8 out of the bottle.
GC dose not have much additive in it and shows low wear, maybe the AW additives are not really needed

 

[Curious Kid]

Were there any tests for fuel dilution on your previous samples? I wonder if this OCI may have had some thus resulting in the thinning of the viscosity, but there's no data given to know this.

Just wondering, that's all.

Interesting.

 

[Idrinkmotoroil]

there wasn't any fuel or coolant detected in any samples taken to date. everything has tested normal.

 

[buster]

Most likely their are some VII in the GC, although very little and this is why it could have sheared a bit. Generally speaking the greater the spread, the more likely it will shear down.

 

[Idrinkmotoroil]

buster, that is what I've always been concerned about with Castrol's 0-30 and 5-40 in turbo applications, but they get a lot of praise in naturally aspirated engines.

 

[vad]

Run it one more time and analyze again.
It takes at least two consecutive runs on the same oil before the things start settle down.
Moving from an oil of dramatically different chemistry can scew the results.

 

[Idrinkmotoroil]

nobadges, you can get your fluid analysis from Toromont CAT much like in my city of London. You buy the kit from them, fill it up with used fluid and take it back to them and ask them to courier it to their lab SOS Fluid Anaylsis.

Triple-Se7en, they list a few more many elements but many of them were zero on my report, there was some sodium and potassium as well but I didn't think that was important to for this post.
They will do oxidation, nitration and soot, and they will do TBN on request, they will also do particle analysis on request, but to me that isn't all that important because I am keeping to short drain intervals with any oil I use. I just listed some of the important elements and viscosity.

My GC batch was from late 2004, I bought it in the fall of 2005 but it was from a 2004 batch, so almost a year old at the time of purchase. I think it sheared due to the turbo, not sure if we've seen many turbo applications on Castrol GC, the other thing is my car has gear driven balance shafts, and that sometimes causes further shearnig of fluids. But I believe most of it is from the turbo heat.

 

[Idrinkmotoroil]

thanks for the advice, hopefully I can still find some more GC to run it a couple more times. The shearing wasn't a big deal, as wear did not worsen and was in line with other oils I ran. The end viscosity was pretty close to the other oils, so no harm done regardless.

 

[JAG]

If this was the first GC fill, this oil being analyzed is a mix of GC and residual oil from the previous "thinner" fill. So this oil should be thinner than pure GC. GC starts out with a viscosity of 12.1 cst or so. Run GC again to get a true GC run. I don't recall ever seeing a UOA showing that GC sheered, even in the sheer-happy VW 1.8T engine. I recall that the GC testing that was done by Terry showed that GC has no VI improvers. It usually actually thickens (from oxidation) because it is so sheer stable. Unlike GC, many oils sheer and oxidize at same time which has a balancing effect on the viscosity.

 

[bulwnkl]

I'm a believer in the notion that the shorter the drain interval, the less you're seeing actual wear metals in an analysis and the more you're seeing a reaction between the new oil and the engine internals. Your drain intervals are quite short so to me it seems logical that you wouldn't see much difference in wear metal levels from oil to oil.

 

[AndyH]

quote:

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Originally posted by Idrinkmotoroil:
My GC batch was from late 2004, I bought it in the fall of 2005 but it was from a 2004 batch, so almost a year old at the time of purchase. I think it sheared due to the turbo, not sure if we've seen many turbo applications on Castrol GC, the other thing is my car has gear driven balance shafts, and that sometimes causes further shearnig of fluids. But I believe most of it is from the turbo heat.

---

I will have a UOA coming soon (probably late January) of green "GC" in my STi (currently running 16.5 psi of boost). Total miles on my GC should be a little over 5,000 miles by the time I get around to draining it. It will be interesting to see if I manage to shear the oil too.

 

[Idrinkmotoroil]

that sounds interesting I look forward to seeing it. I think all of my oils showed a bit of shearing, but the GC has he largest drop. Like mentioned above it could be from residual oil, but I don't think all of it would be from that, perhaps a bit of lab error and some actual shearing , combined.

I had less oil consumption with GC, Mobil1 and even Redline has higher consumption levels, about twice as much as the GC.