Can someone explain the 0w theory?

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167
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chicago burbs
I just recently started to hear about 0w/30, 0w/40 ect. and been wondering about them. I understand that at start up your oil w is 0. So is it safe to use for a nissan maxima that calls for mostly 5w/30? Should it only be used in winter and short trips? Is it better to use it then 5w/30 Being able to flow better at start up?
 
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23,591
Without knowing the hard figures, I'll just say that 0W-X oil has a lower pour point than 5W-X, but we are talking about extremeley low temps here. Think -40 degr F and down. I think it's questionable if an oil pump will be able to pump either oil at those temps. I think the difference between 0W-X and 5W-X oils is academic at best.
 
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8,937
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SC
The only situation where a 0wXX oils is a MUST is in very (and I mean VERY) cold climates. In more moderate climates, a 5wXX or even 10wXX oil is just fine. Once the oil reaches operating temp, there will be very little difference in the viscosity of a 0w30 and a 10w30, hence for any engine that can safely run a 10w30, a 0w30 should do just fine. Modern advances in base oil technology is why you're seeing more and more 0wXX oils. Oil companies want to take advantage of the low temp and low friction properties a 0wXX oil has, and it's the inherent high VI of the Group IV and Group V base oils that allow them to do that while at the same time meeting the high temp specs of a 30wt or 40wt. NB: Everything in my answer pertains to synthetic oils only. For example, there are moderate climates that get cold enough in the winter where I would not want to use a CONVENTIONAL 5w30.
 
0Wx oils are desirable for startup and warmup in any climate for many newer cars; indeed it is the recommended oil by many automobile manufacturers. They feel, I surmise, that it is paramount to get OHCs and valvtranes lubed as quickly as possible and heavy oil at startup just doesn't cut it. For some cars 0Wx is almost a necessity; in others it's a good-to-have to reduce wear and provide better lubrication, even in warmer weather. A good 0Wx will do everything a 5Wx will, and more, if I am reading the spec sheets and oil analysis correctly.
 
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A 0W- rating on oil is no theory and has nothing directly to do with pour point. A 0W- oil has passed a viscosity test at -35°c. A 5W- oil is tested at -30°C, and a 10W- tested at -25°C. http://www.chevron.com/prodserv/NewOronite/library/li_viscosity_motoroil.htm Some of the 0W- oils are a different formulation, not just a different viscosity. Mobil 1 0W-40 is a better oil than the Mobil 1 xW-30 oils as evidenced by the ACEA A3 rating on the 0W-40 and the ACEA A1 rating on the xW-30 oils. Ditto for the Castrol Syntec 0W-30 made in Germany. Ken
 

trey

Thread starter
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167
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chicago burbs
Hmm, getting some good reply's here, but from what i read, 5w/30 should be fine for my applications in chicago here.
 
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quote:
Originally posted by Ken2: Mobil 1 0W-40 is a better oil than the Mobil 1 xW-30 oils as evidenced by the ACEA A3 rating on the 0W-40 and the ACEA A1 rating on the xW-30 oils.
This just isn't the case. That Mobil 1 0w30, 5w30, and 10w30 don't carry the A3 rating is not a DEFECT in these oils; they were not designed to be A3 oils. They are A5 oils, and A5 is just as tough an extended drain spec as A3, it's just the newer "low friction, low HT/HS" ACEA spec.
 
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Dixie
I'd have to agree with Ken2 about the relative merits of ACEA A3 vs A5.... The primary reason for the mininum high temp/high shear viscosity of 3.5 Cp as part of the A3/B4 specifications is to prevent wear under high temp/high load conditions. An oil that is 15%-20% thinner isn't going to provide the same oil film thickness in the bearings or valvetrain under these conditions. With thinner oils I believe you do rely more on the antiwear additive chemistry. It is true that the A3 and A5 test sequences have the same limits on wear and deposits, but you have no way of knowing with how much margin the 0w-40 passed these tests in comparison to the xw-30 formulations. Most of the top tier OEM oil specifications in Europe are based on ACEA A3/B4 as a starting point and then add manufacturer specific tests in their own engines. I do think that the A5 oils should be as durable as the thicker A3 formulations, but I haven't seen data that shows they provide the same level of protection for engines that aren't specifically designed to use low vis oils. Tooslick
 
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Correct, although not a defect as pointed out the truth still remains that in the case of M-1 the 0-40 is a better oil product than their 0-30 or 5-30/10-30 for that matter...
 
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529
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Manitoba, Canada
quote:
Originally posted by Ken2: A 0W- rating on oil is no theory and has nothing directly to do with pour point. A 0W- oil has passed a viscosity test at -35°c. A 5W- oil is tested at -30°C, and a 10W- tested at -25°C.
Yes, I remember realizing that the numbers have zero to do with pour point, and that is a large, and somewhat counter-intuitive, realization. Can anyone explain how this relates to them passing a visc test at those temperatures, then? Or is passing the test rather meaningless, too?
quote:
http://www.chevron.com/prodserv/NewOronite/library/li_viscosity_motoroil.htm

That link seems to have been secured in the last few days Cheers
 
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Gone
I've come to the conclusion that as long as an oil is well formulated (including a solid additive package) and doesn't shear excessively I'll take that 0W "quick to the parts on startup" oil flow any time...now if someone can SHOW me empirically that the time differntial from pan to top end on start up between a 0W, 5W and 10W is inconsequential, I'll re-think.
 
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Rob, I said that the "W" viscosity has nothing directly to do with pour point. The pour point for a lower vis oil is also likely to be lower, but there is not necessarily a direct relationship. I feel that a more important measurement of the oil for severe winter use than pour point is Borderline Pumping Temperature. The "W" viscosity ratings are very important for cold starts and cold running. This is the actual measurement of the oil's flow and resistance at the specified temperatures. Ken [ July 13, 2003, 02:56 PM: Message edited by: Ken2 ]
 
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529
Location
Manitoba, Canada
Absolutely; if there is snow on the ground and your oil doesn't have a W in it, there are some issues going on [Wink] Look around you can see 20W50's with pour points around -40, and 5W30's with pour points not nearly as good as that. Lucky we have this forum to clarify stuff like that. The borderline pumpability is far more 'real-world' yet a lot of companies don't share that too well [Wink]
 

Jay

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1,607
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Idaho Falls, ID
quote:
Originally posted by TooSlick: I'd have to agree with Ken2 about the relative merits of ACEA A3 vs A5.... The primary reason for the mininum high temp/high shear viscosity of 3.5 Cp as part of the A3/B4 specifications is to prevent wear under high temp/high load conditions. An oil that is 15%-20% thinner isn't going to provide the same oil film thickness in the bearings or valvetrain under these conditions. With thinner oils I believe you do rely more on the antiwear additive chemistry. It is true that the A3 and A5 test sequences have the same limits on wear and deposits, but you have no way of knowing with how much margin the 0w-40 passed these tests in comparison to the xw-30 formulations. Most of the top tier OEM oil specifications in Europe are based on ACEA A3/B4 as a starting point and then add manufacturer specific tests in their own engines. I do think that the A5 oils should be as durable as the thicker A3 formulations, but I haven't seen data that shows they provide the same level of protection for engines that aren't specifically designed to use low vis oils. Tooslick
Your reasoning that "thicker is always better" is flimsy, TooSlick. An engine that needs A3 oil will certainly benefit from the A3 oil, but where is the evidence that an engine that is designed to run on A5 or A1 oil will benefit from an A3 oil? An analogy would be gasoline octane. An engine designed to run on 92 octane benefits from 92 octane gasoline. Will an engine that runs fine on 87 octane benefit from 92? No. I agree with G-Man II. Each ACEA category has a specific set of standards for each viscosity. All viscosities are held to the same wear and deposit standards by ACEA. To say that ACEA A3 is "higher" than any other standard is a purely subjective opinion. I could just as easily say A1 or A5 is the "highest" standard because they have the the most stringent gas mileage requirements while meeting the same wear and deposit requirements of A3. [ July 19, 2003, 02:33 PM: Message edited by: Jay ]
 
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