5W-30
10W-30
No bearing on the operational viscosity (thickness) of the oil ([email protected] 100*)
10W-30
No bearing on the operational viscosity (thickness) of the oil ([email protected] 100*)
Viscosities: Mobil 1 5w30 vs 10w30?
- Thread starter JonnyAbs
- Start date
I was so surprised that they were so close at 40. It was the lowest measurement I had for comparison.
I'm starting to think that all the 0W-xx, 5W-xx and 10W-xx oils (where xx is the same hot viscosity rating) are going to be basically the same "viscosity vs temperature" from 40C and higher (as seen in the examples I plotted). Maybe that's why they have chosen 40C as one of the viscosity temperature points in the specs.
I definitely agree and thats why I also wish they included 0 also or even instead. Even in areas where its 40C, its not that all year round. Even in Florida or Texas, I think it ocassionally approaches freezing, and cold is where you really want to know the flow.
Actual regression is molded by choice and combination of VM these days. You cannot be serious in discussing the fictive curves derived from KV40 and KV100 – but yes, by zooming out from the once plotted fiction you can certainly progress to a discoidal world of xx-viscosities, turn that around and expect anything you like for 40C and below. Just do it, somehow they all fit the big NIKE curve...
Yes certainly, at the temperature of your winter rating, none of your bearings are going to be on the operational viscosity.
You got anything better, like measured viscosity at many other temperatures besides 40 and 100C to determine just how "fictitious" Widman's curve generator is?
OVERKILL
$100 Site Donor 2021
We know that visc calcs don't work much below 0C, so I'm not sure what the point is of trying to run it down to -40 and play "Gotcha!" 🤷♂️
Can you give info/data that proves they don't work well below 0C? ... ie, real viscosity vs temperature measurements shown against the calculator model output.
OVERKILL
$100 Site Donor 2021
Sure, I've posted it in the past, I'm surprised you didn't see it in many of the numerous discussions we've had on this subject? Molakule has chimed-in on it as well.
Take a straight PAO base that lists viscosity at multiple temperatures. PAO has no wax in it, so it's about the purest example we can work with here. Bases with wax that can crystallize and require PPD's will not behave as well.
So, using SpectraSyn 8, which lists KV at multiple temperatures:
KV100: 8cSt
KV40: 48cSt
KV-40C: 18,000cSt
Plug that in your visc calc and it shows 33,262cSt at -40C.
Feel free to try this with some of the other bases. The only one that plots correctly is SpectraSyn 2, all of the others are off massively. And now, again, consider we are using pure PAO which has VERY predictable performance and a fully formulated lubricant won't behave even remotely close to as predictably.
Most of those 10 oils shown they act very similarly with temperature change. Odd ball oils don't necessarily define the whole phenomenon, especially when the VM formulations of "oil #1 thru oil #10" isn't defined.
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Gokhan's sheet to a degree copes with such "odd ball" oils like Mazda's Original Supra or the ENEOS Street Racing when erecting its HTFS-V fiction whereas this thing has no chance to discriminate very different KV100 data, be they boosted in one or another way or basically base oil data.
This of course is only a part of the problems. The question is what intervals you'd want to rely on and how?
This of course is only a part of the problems. The question is what intervals you'd want to rely on and how?
Just to clarify, the purpose of showing the V vs T plots was to see how 0W-xx vs 5W-xx and 5W-xx vs 10W-xx compared from 40C and above, which showed that the viscosity vs temperature was basically identical above 40C.
As far as "running it down to -40C", can anybody please show me where an oil rated at 0W-xx has a higher viscosity than any oil rated at 5W-xx, or an oil rated at 5W-xx has a higher viscosity than any oil rated at 10W-xx anywhere below say 0C. I highly dougt there are any, because if there was they wouldn't be rated at 0W, 5W or 10W to start with.
When plugging in KV40 and KV100, the temperature at 19,000 cSt (as data sheet shows for KV-40, not 18,000 like you posted) comes out to -36.1 C. Nobody (even Widman on his website) claimed the calculator was dead nuts accurate ... but being only 4 deg C off isn't bad IMO since viscosity it super sensitive to change the colder it becomes. Besides, use the "W" rating for cold weather oil picking.
OVERKILL
$100 Site Donor 2021
You weren't the guy running it down to -40C. My point was that somebody doing that exercise and expecting accurate results, well, shouldn't be. Visc calcs aren't designed to be used much below 0C because their accuracy goes out the window, so don't expect them to plot the same as CCS and MRV does; don't expect CCS and MRV to support what somebody has spit out of a visc calc at those temperatures because it won't.
I SPECIFICALLY used straight PAO because it was going to be the closest, and even it was WAY off. Now consider the impact of wax crystal formation, PPD's, VII's, additive packages...etc. That's why you go by the Winter rating and the available figures for that, if possible (CCS/MRV), rather than whatever exercise was being performed using the visc calc (which wasn't you doing it, let's be clear on that point).
This explains what it's meant to do.
But inverting relations for CCS viscosities means a need to decide what to do with a third pic going to 0°C or whatever (to compare KV40 data it's not needed and everywhere inbetween 40°C and 100°C it would have difficulties again).
This third pic looks much like the first one – same problem of inversion, same "questions". Take out your pencils if you can't find the right words...
But inverting relations for CCS viscosities means a need to decide what to do with a third pic going to 0°C or whatever (to compare KV40 data it's not needed and everywhere inbetween 40°C and 100°C it would have difficulties again).
This third pic looks much like the first one – same problem of inversion, same "questions". Take out your pencils if you can't find the right words...
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Being off 4 deg C for KV-40 when viscosity change is super sensitive at those temperatures isn't too bad IMO. Obviously, there's a reason or two the oil makers don't show the KV at temperatures that cold level and use the "W" ratings, because a few degrees can make a huge viscosity difference ... not so much at say 40C and above, or even 0C and above.
OVERKILL
$100 Site Donor 2021
Correct, but again, that's for STRAIGHT PAO, which has NO WAX in it. It's performance is as predictable as you are going to get. A fully formulated lubricant isn't going to be anywhere near as predictable.
I believe the threshold we previous discussed was around -10 to -15C as to where the visc calc figures really seem to come apart for fully formulated oils. Of course oils blended with PAO will stick closer than those that aren't, so will probably plot closer down further.
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