VI is a standard measure of the rate of change of viscosity to temperature. The higher the VI, the lower the rate of change. Kinematic viscosity is the viscosity that we're interested in when talking about pour point. Kinematic viscosity is measured under the flow of gravity (i.e. very low shear rates) as is pour point. Dynamic viscosity (the viscosity that you're link refers to) is a different property altogether. It's kinematic viscosity times density and is used to measure viscosity at high shear rates.quote:
Originally posted by G-Man II:
I don't think anything is amiss. What I do think is that at extreme temps like -81°F these calculations are meaningless (and are probably not even accuarate). cSt vis is meant to be a measure of a HOT oil's viscosity. The viscosity index was never meant to indicate an oil's resistence to thickening at cold temps; it was meant to show an oil's ability to resist THINNING at high temps, with 40°C as the established baseline, and 100°C as the upper limit. These were considered the operational parameters of a motor oil back when the concept of VI was first developed (which was in the late 1920s, I believe).
Cold vis is calculated and measured differently and is reflected in the cold cranking viscosity number, which is measured by ASTM D-2602, and gives the "apparent" vis of the oil at low temps. The measurement unit is in centipose (cP).
As an example of how two oils with identical VIs, which are the same viscostiy at higher temps, can behave very differently at colder temps, take a look at this page comparing a VHVI base oil to PAO.
'Nuff Said!!!!quote:
Originally posted by Patman:
Like this (from my sister's 99 Civic):quote:
Originally posted by Tim H.:
OK, weather it peforms at cold is one thing, and hot is another. but what is it going to look like at 5000 miles?
code:
Mobil 1 5w30 Castrol 0w30
8000 miles 5500 miles
.
Iron 19 14
Lead 10 4.5
Aluminum 5.2 2.5
Copper 3.8 3.0
Silicon 8 11
Nickel 0.1 0
Chromium 3 0.8
Titanium 0.1 0
Tin 0.2 0
Silver 0.4 0.2
Vanadium 0.2 0
Potassium 0 0
Sodium 6.5 1.5
Boron 118 16
Barium 0 0.1
Manganese 226 149
Calcium 2834 3003
Magnesium 50 129
Moly 82 15
Phosphorus 902 781
Zinc 1091 998
Fuel 0 0
Glycol 0 0
Water 0 0
Sulfation 49% 23%
Oxidation 51% 29%
Nitration 37% 21%
VI 174 182
Vis @ 40c 50.6 62.1
Vis @ 100c 9.5 11.5
TBN (D4739) 5.27 6.90
Not when the question was "but what is it going to look like at 5000 miles?"quote:
Originally posted by GROUCHO MARX:
Does the fact that the M1 interval was 45% longer mean anything?
Its' not really a fair comparison. For one, M1 has been tweaked. I'm not saying the GC isn't as good or won't be better, but you can't base much off of one UOA, as the Redline lovers will tell you.quote:
'Nuff Said!!!!
G-man, I just picked some oil specs at random and used the viscosity calculator that I posted earlier to calculate the kinematic viscosity at their pour points.quote:
Originally posted by G-Man II:
Jay, where are you getting these "frozen" figures for oils from?
And until I see proof otherwise, I'll assume that based on the industry standard tests used, the pour points listed for any oil on the manufactuer's data sheet is valid and accurate—no matter how "unbelievable" any particular one may seem.
So the viscosity calculator is a legitimate way of calculating Kvis from pour point to about 300 deg F.quote:
...it is necessary to have some method of determining the viscosities of lubricating oils at temperatures other than those at which they are measured. This is usually accomplished by measuring the viscosity at two temperatures, then plotting these points on special viscosity-temperature charts developed by ASTM. A straight lined can then be drawn through the points and viscosities at other temperatures read from it with reasonable accuracy...The line should not be extended below the pour point or above approximately 300 deg F since in these regions it may no longer be straight.
I'm with Pablo on this one. People are making to much of a big deal of this GC. I can order Amsoil or buy M1 and get great results. I won't have to wonder around the country looking for it either. And lets see the GC match Pablo's results!!!quote:
OK OK GC is the BEST oil ever.
But why are my 20,000 mile results about the same as above? Plain vanilla Amsoil ASL 5W-30 . $4.50 qt. Order today, arrive tomorrow.
Funniest thing? People gripe about Amsoil availability. I have NEVER seen a bottle of GC.
'nuff said. I'm going back to my cave.
It's not really a direct comparison between M1 and GC because of the mileage difference, but do look at the data of GC on it's own, for a 5500 mile run it looks very good, especially since that was the first run with this oil. The TBN is still very strong, and it's on the lower scale too, and oxidation/nitration are good (and will go down with the second interval)quote:
Originally posted by GROUCHO MARX:
Does the fact that the M1 interval was 45% longer mean anything?
Just asking.
Amsoil is definitely one of the best oils out there, I recommend it to my US friends with LS1s and LT1s all the time. But here in Canada, it's easier for my friends to pop into Walmart, or Canadian Tire, and pay $6.29 to $6.66 per liter for GC than it is to try and find an Amsoil dealer, and pay $9 to $10 per quart. Even when I used to be an Amsoil dealer myself, I paid more for Amsoil at my cost than Mobil 1 was selling for at Walmart! So it's a hard sell up here based on that. I only know one guy in my car club who uses Amsoil. Most of the rest use Mobil 1, but one or two have started buying GC.quote:
Originally posted by Pablo:
OK OK GC is the BEST oil ever.
But why are my 20,000 mile results about the same as above? Plain vanilla Amsoil ASL 5W-30 . $4.50 qt. Order today, arrive tomorrow.
Funniest thing? People gripe about Amsoil availability. I have NEVER seen a bottle of GC.
'nuff said. I'm going back to my cave.