XD-3/GC 0W-30 vs. ACD - cold crank proerties

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Esso XD-3 0W-30 and GC 0W-30 are similar synthetic oils - both primarily PAO, HD oils that meet the cold-crank specs for a '0W' oil (less than 6200cp @-35C). They are both failry thick, being 'around' 70cst @40C; and 12cst @100C. One thing that has been said, but not entirely 'proven' about these oils is that they most likely DON'T use VII's - they are straight-weight PAO's that meet the '0W' spec. Amsoil ACD is also a primarily PAO, HD oil, but it is thinner - about 66 [email protected] 40C, and only 10.5cst @100C. It 'only' meets the cold-crank specs for a '10W' oil (less than 7000cp @-25C). It is stated by Amsoil that this oil is VI-free. If the Amsoil ACD has a similar make-up to XD-3 and GC, and is actually thinner, shouldn't it ALSO be able to meet the specs of a '0W' as well, not just a '10W' oil?
 
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And I don't consider that a knock on GC, as I think it's an exceptional oil with few peers (in North America, at least). The fact that someone would believe it does not contain any VII's is credit to the quality and shear stability of the VII it does make use of.
 

JHZR2

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You might say that the ability to meet 10W and being thinner at certain temperatures provides a certain slope of the temperature/viscosity curve. Slope may notbe accurate, as nonlinearities surely exist. The difference will be the slopes of the curves. You might say that the ACD has a steeper downward slope, so it thins at a lower temperature and is thinner at 100C. GC may have a milder slope, which allows it to be better performing at -35, but slightly thicker at 100C.
 

addyguy

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Yeah, I'd like to viscosities at 0C, -10C or -15C. For a lot of people in the 'population belt' of Southern Ontario and Quebec, even -20C isn't THAT common on a sustained basis....
 
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I would also love to see oils rated at freezing. That's a worst case scenario where I live.
 
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 Originally Posted By: zoomzoom
I am willing to bet that at 0C GC is thicker then many 5w-30 syn oils
no need to bet, it's a fact If you lookup the GC viscosity index, and its' 40 or 100 degrees cst you can find the cst at any given temp using the following link (module 4): http://us.geocities.com/cichen.geo/VI.html I've played with it quite a bit and it is accurate. PP 5w30 seems to be one of the easiest over-the-shelf oils to pump in freezing temps.
 
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 Originally Posted By: addyguy
One thing that has been said, but not entirely 'proven' about these oils is that they most likely DON'T use VII's - they are straight-weight PAO's that meet the '0W' spec.
How would that be possible? Or is multi-viscosity a characteristic of any PAO based product?
 

addyguy

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AFAIK, yes - any synthetic base oil has a very high natural VI, so it can meet a lower temp spec without the need for VII's. I've read here many times that almost all modern 10W-30 synthetics are VII-free, or have very, very little.
 
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 Originally Posted By: ArcticCat
I strongly doubt that GC and Esso XD-3 0W-30 are VII free given their extremely high viscosity indexes.
Remember, a few years back, a bunch of us chipped in to have a GC/MS done on GC (back in the green days). Although we are not permitted to disclose the specifics, I can say a few things in response to this comment. GC does not appear to have conventional VIIs. It does appear to include certain relatively "exotic" base fluids whose "natural" vis index is extremely high. Keeping in mind that I'm neither a tribologist or a chemical engineer (OK, I admit it, I'm a lawyer...), as I interpret the results we got, the Green GC contained esters that, in effect, served as both a component of the base oil mixture, and a VII. I readily admit that I may be interpreting that info incorrectly. Nobody, to my knowledge, has undertaken such an experiment with the current "gold" colored version of GC, though I suspect it's not too much different from the older green variant we all went ga-ga over five years ago.
 
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 Originally Posted By: webfors
 Originally Posted By: zoomzoom
I am willing to bet that at 0C GC is thicker then many 5w-30 syn oils
no need to bet, it's a fact If you lookup the GC viscosity index, and its' 40 or 100 degrees cst you can find the cst at any given temp using the following link (module 4): http://us.geocities.com/cichen.geo/VI.html I've played with it quite a bit and it is accurate. PP 5w30 seems to be one of the easiest over-the-shelf oils to pump in freezing temps.
I agree. GC's "0w" rating is not a measure of its "thickness" or more properly viscosity, while cold. Rather, it stems from this oil's "freaky" ability to remain liquid and pumpable at very low temps that would leave most lesser thinner oils (especially the lower end conventional 5w-30s) a congealed, solidified mess.
 
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