Watch out, some people on here can't understand joking around. Someone will take you serious.
Viscosity
- Thread starter free2d
- Start date
Here's a couple of example "viscosity vs oil temperature" curves for 5W-20, 5W-30 and 15W-50 for comparison purposes. The low temperature only goes down to 0C (32F) on the graph, but it shows the fact that if an oil has a higher KV40 viscosity than another oil, then it will also have even higher viscosity difference below 40C as the temperature decreases compared to the other oils. The 2nd plot is a "blow-up" of the same oils in the upper temperature range to better see the difference in viscosity from 80C up to 180C.
If they can send me a link to a 0w100 oil that I can buy...
I've got some -20w200 you can buy off my shelf.
Look at the KV100 (Kinematic Viscosity at 100C) between those two oils, then go find where the KV100 (cSt 100C on the LH side of the chart) falls on this viscosity grade chart and you'll see if that is true or not.
Dude - guys asking questions on an oil forum - thats how you learn. Chill out.
Viscosity at 40c and 100c is a two point of reference to understand how different oils perform along a range of temperature. By plotting these two points were able to determine what viscosity an oil will provide at operating temperatures. It has nothing to do with cold starting. Although there is a linear relationship. Viscosity is determined by the quality of the base stock, additives and performance characteristics. When looking at an SAE Grade of 15w40 for example that refers to a viscosity of 15 at 100c and a winter (W) of 40. But thats a generic grade used to easily classify an oil for commercial sale - oil manufactures finished products can often be very different (between 10-20%) fluctuation of those numbers. A conventional, blend and full synthetic will all "hold" there viscosity differently within the grade. And pour point is more tied to the quality of the oil (or a ton of pour point depressants). If you look at a conventional or blend 15w40 it will have a pout point in the -20's and lets say a viscosity of 122.1 cst @ 40c and a viscosity of 16 cst @ 100c (Spectra Xtreme 15w40 blend is the reference). As where a 5w40 (being a full synthetic) has a pour point of -46 c a vis of 91.4 cst at 40c and a vis of 15.3 cst at 100c (Spectra Xtreme full syn 5w40) - in this example a full synthetic will pour better in the winter, have a lighter vis in the low temp ranges (making it easier to get lubrication going) and almost as stable of a vis at 100c (212 F typical operating temp but not always). The quality of the full synthetic and all of the properties synthetic oils provide can essentially provide the engine protection of a 15w40 with way more advantages.
I often see people making flawed assumptions about 0 weight oils. Thinking they will always provide better cold flow. And its simply not true. A conventional 0w20 will more likely be a lesser product than a blend or syn 5w20. Whats important is what youre equipment is looking for in terms of engine protection at its operating temperature (viscosity)
If "oil A" has a lower viscosity at 40C then "oil B", then "oil A" is also going to have a lower viscosity at temperatures below 40C. Don't let 40C hang you up. Speaking of the viscosity vs temperatureo use Widman's viscosity vs temperature calculator and look at the plot curves of different oil's using their KV40 and KV100 data points and you'll see what I mean.You might want to try grasping the words a bit better before starting off a reply like that ...I was talking about comparing different viscosities to each other in a simplied matter. Oils with a lower KV40 will also be thinner at lower temps than oil with a higher KV40. and therefore will provide better cold starting in cold conditions. And oils with a higher KV100 will provide better protection when the oil is at 200+ F. It's a well know fact of tribology that thicker viscosity provides more MOFT which gives more protection from moving parts contacting each other and causing metal-on-metal wear. You've been here since 2005 and should have read that about 1000 times over the years.
If "oil A" has a lower viscosity at 40C then "oil B", then "oil A" is also going to have a lower viscosity at temperatures below 40C. Don't let 40C hang you up. Speaking of the viscosity vs temperatureo use Widman's viscosity vs temperature calculator and look at the plot curves of different oil's using their KV40 and KV100 data points and you'll see what I mean.
Anyway ... apology accepted.
What he said here! Graphing Viscosity is about understanding the base stock performance over a range of temperature.
4WD
$50 site donor 2024
Winter of 40 ? Does that work well in the cold ?
We use multi grade oil up here. I run a full synthetic 5w20 in my Ford Edge. It pours to about -38 - If i dont plug my car in. My vehicle starts everytime. But - I always plug my vehicle in to keep the oil warmer in deep cold. So cold starting is a non issue for me.
In regards to a 40 weight. Yes they work fine. A conventional 15w40 might not start that well if you dont plug youre car in. Youll have a hell of a time pumping that oil in -40.
OVERKILL
$100 Site Donor 2021
That's not remotely close to accurate.
The 15W indicates the oil's ability to pass the CCS and MRV requirements to meet the 15 Winter designation as per SAE J300, which defines a ceiling for both CCS and MRV at two different temperatures 5C apart.
Winter Rating/CCS/MRV
0W -35C/-40C
5W -30C/-35C
10W -25C/-30C
15W -20C/-25C
20W -15C/-20C
The number AFTER the W is the SAE grade designation at 100C, for which there are ranges. For an xW-40 that range is 12.5cP - <16.3cP.
Is there such a thing as conventional 0W-20 oil?
OVERKILL
$100 Site Donor 2021
I think at minimum it would need to have some Group III blended into it, so it would be a syn blend. I know XOM's Group II+ products are quite capable but I don't think they are quite THAT capable.
I'd recommend reading through this site's Motor Oil University pages - it covers the basics and then some:
Motor Oil 101 - Chapter One - Operating Temperatures and Viscosity - Bob is the Oil Guy
Chapter One Understanding what viscosity grades mean can be confusing. The average driver just tries to follow what is in the owner’s manual – this is a good practice. Some owner’s manuals allow for different grades based on the predicted operating temperature. For example, they may specify a...
bobistheoilguy.com
4WD
$50 site donor 2024
Yeah … seems a majority Grp3 is needed …
but even if 70/30 sold in large quantities ? money in the bank …
They're probably talking about HTHS viscosity, there's only a minimum regulated.
