0w-30 over 5w-30?

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Originally Posted by geeman789
Originally Posted by PimTac
I may be wrong here but my understanding is that the difference between 0w and 5w is around 5 degrees of cold weather performance. When it's -30F, another 5 degrees won't matter much. It's already cold and one should be taking other actions to keep things fluid.
A 5w oil does not exceed the maximum viscosity limits at -30*c and -35*c, but becomes too thick to meet these requirements at -35*c and -40*c. So, only 5*c colder moves the oil from functional to questionable in flow and pumpability. At temperatures around -30F is where it matters MOST ...
Yes and another point, these oils don't just stop pumping at -30 or whatever the specs say. There are a lot of variables involved. It also depends on what the meaning of functional is.
 
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Originally Posted by geeman789
Originally Posted by pbm
I've always found it perplexing that some 0w30's like German Castrol and Esso XD3 are actually more viscous (thicker) at 0*F to 32*F (normal winter temps in my area) than some 5w30s....
And you know that how ?
I wouldn't doubt that. I looked at viscosity vs. temperature graphs for Mobil 1 0w-40 vs Mobil 1 5w-30 and found out that in the moderately cool ambient temp ranges around 20-50 deg F....that the 0w was thicker than the 5w. So for my particularly semi-mild winter temps (30-45 deg F) it would make more sense to use the 5w-30. It would not surprise me in the least if the Castrol 0w-30 vs 5w-30 has similar characteristics....as the 0w-30 Castrol Edge and 0w-40 Mobil 1 used to be fairly similar in their viscosity attributes. This was 2-3 yrs ago....the oils have been modified since....and the charts could be different now.
 
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Originally Posted by PimTac
Yes and another point, these oils don't just stop pumping at -30 or whatever the specs say. There are a lot of variables involved. It also depends on what the meaning of functional is.
What is functional ? This video has a cold ( -40*f ) pour test of T6 5w40 vs T4 15w40. Both oils do actually pour ... slowly. The 15w40 pours VERY SLOWLY. But it does move, so is that functional ? Go to the 7:05 mark for test. https://www.youtube.com/watch?v=Pa4RwsiZUmI
 
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The question of the meaning of functional cane from your comment above. "So, only 5*c colder moves the oil from functional to questionable in flow and pumpability."
 

pbm

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Originally Posted by geeman789
Originally Posted by pbm
I've always found it perplexing that some 0w30's like German Castrol and Esso XD3 are actually more viscous (thicker) at 0*F to 32*F (normal winter temps in my area) than some 5w30s....
And you know that how ?
I remember reading info about it on a site called BITOG years ago....J/K.....I actually have some of both in my stash but haven't found a use for them. kschachn's answer about the winter rating being determined at very low temperatures is correct but it's easy to see how an uninformed person would assume that 0w30 must be better for cold starts at any temperature...
 
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Originally Posted by kschachn
Originally Posted by pbm
I've always found it perplexing that some 0w30's like German Castrol and Esso XD3 are actually more viscous (thicker) at 0*F to 32*F (normal winter temps in my area) than some 5w30s....
That is because the winter rating is determined at very low temperatures. Much misunderstanding about what the rating means and is determined.
Yes, and many people do not have a good understanding of their own climate. I was talking to someone last week about winter ratings and he was adamant you NEED a 0W rated oil in our part of Massachusetts - I had just looked this info up and pointed out the lowest recorded temperature our part of MA was -24F in 1934, we only average four days per year below 0F and there have only been 10 days below -15F since 1892. We do average 142 days per year where we reach below freezing but any 5W oil should do just fine here IMO. For anyone trying to decide 0W vs 5W just look up your climate data...it's all out there on the interweb.
 
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Originally Posted by geeman789
Originally Posted by PimTac
Yes and another point, these oils don't just stop pumping at -30 or whatever the specs say. There are a lot of variables involved. It also depends on what the meaning of functional is.
What is functional ? This video has a cold ( -40*f ) pour test of T6 5w40 vs T4 15w40. Both oils do actually pour ... slowly. The 15w40 pours VERY SLOWLY. But it does move, so is that functional ? Go to the 7:05 mark for test. https://www.youtube.com/watch?v=Pa4RwsiZUmI
Then you have the idea that Jello doesn't pour - but you can pump it. Thus the combination CCS and MRV for determining extreme sub zero serviceability. Then your water pump seals, axle seals, CV boots and wheel bearing greases, shock seals and timing belt and accessory belts and alternator bearings are all at high risk to damage and failure. I know I lost a few from the above list on a newish Toyota on one of those -15F winter weeks in New Hampshire
 
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Originally Posted by 69GTX
It was only 3-7 yrs ago that some of the 0w-30's were nearly 40 grades. Castrol got the most notoriety with their Belgium Edge 0w-30 full synthetic (SL and SM specced?). I guess with the shift to SN and SN+ these may no longer exist. But it wasn't long ago that performance 0w-30's were much thicker at normal operating temps than the 5w-30's (11.0-12.0 cSt at 100 deg C vs. 9.5-10.5). No doubt some of old stuff is still in people's oil stashes.
Euro A3/B4/C3 0w30's with their min HTHS of 3.5 are a dying breed.
 

blupupher

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Originally Posted by PWMDMD
... For anyone trying to decide 0W vs 5W just look up your climate data...it's all out there on the interweb.
If you go by that, I can run a SAE 30 year round since SAE 30 is good to about 20°F (not that you can readily find SAE 30 any more). Average low in January is 42°F, and probably get 5-7 days a year below freezing, with an outlier in the teens every decade or so. 10w-30 and 15w-40 oils are fine to run around here in motors with a xw-30 spec as far as temperature concerns. As for the OP question, I consider 0w and 5w as interchangeable in all but the coldest of climates.
 
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