GC vs. M1 0w40 visco

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BobFout

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Recently bought some GC to add to my stash of M1 0w40, RP 0w40 and RL 0w40. Yeah, I have an oil problem
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Anyways, did some visco calcs comparing the two:

GCvsM10w40.png
 
That's calculated viscosity at a given oil temp. (in cSt)

You know what... that chart is wrong though. I misread the Castrol datasheet. They don't give visco at 40*C.

Oh well, nevermind my thread! Sorry!
 
Just add the 100C and 40C numbers on the bottom set by the graph and it will graph up to 3 different oils for you.
 
Also, the boxes in peach color are inputs, just enter numbers and hit enter and the graphs and stuff will automatically update.
 
Honestly, i dont remember as it has been almost six months or a year since i have done this but "I" did not come up with it. I found a guy that was in the oil business that sent me to a website with official equations. Once i found what the equation number was, i did some goggling for that equation and believe that i found this equation as it sits and just converted it to excel format. Rhomax has a blending calculator and this matches theres so i am fairly confident that all the math is correct. but it is just the exponential of the natural log of the weighted sums. Most people by default think you can blend the two oils and then just take the avg, but it dont work like that. Also i believe this may be a standard fluid dynamics equation. I have a post on bitog called " an excel file i would love to share" if you find that, i have links to online calculators such as Rhomax and widman viscosity grapher, so you can feel confident that the math is correct. I wanted to make this a bitog sticky somewhere because every day i see a "what if i mix this" or "which is better in the cold" type questions but really it never caught on. I had a few email me and were interested and i believe still use it but only about 10 or so were really interested. Anyway, was this the info you were looking for or did yow want the actual official equation number?
 
Thanks for the explanation. I was also one who assumed blending could be described by simple averaging. I'll find the thread you mentioned and see if I can find the governing equations. I'd like to understand this topic better.
 
Here is the link to my other post. let me know if you come up with anything interesting in your research. Im not a professional oil blender or anything, i just find this stuff very interesting and fun to play around with. Also any feedback on the excel sheet would be great. My goal was to make it very user friendly and helpful to the general public, or at least bitog folks.

https://bobistheoilguy.com/forums/posts/1812731/
 
Originally Posted By: emaax
these oils are totally different, besides the differences in viscosity



Totally different? These are the specs they share in common.

ACEA A3/B3/B4
VW 502.00 / 505.00
MB 229.3 / 229.5
BMW LL01
GM-LL-A-025
GM-LL-B-025
 
Originally Posted By: cp3
So running GC/PP 5W30/PYB 5W30, the GC is still thicker at lower temps, almost the same a PYB, higher than PP. So how does this rate as a 0W30 and not a 5W30?


The 0w or 5w delineation is at a temp well below zero F, something like -20 to -30?
 
If they labeled it as a 5w30 oil I would have more difficulty in finding it at Autozone.Since it is a 'weird' weight people do not buy it.
 
Thanks, really interesting comparison. I've been thinking about using some of the GC for my winter fill, especially since I have a stockpile of the stuff!
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