Interesting oil comparison

[Zenermaniac]

It’s raining and I was bored so was looking at oil specs. As you know MG recommends Agip/Eni 10W60 for many of our bikes. I’ve been using Castrol Edge 10W60 because it is available locally though getting harder to find. In various oil threads Mobile One 15W50 and Mobile One V-Twin 20W50 always come up.
Using the Widman.org calculator I wanted to see how all four compare. At high operating temps all four are really very close. The Agip and Castrol are almost identical across all temps. In cooler climates the Mobile One 15W50 has the edge over the other three as far as cold starts. Maybe it’s splitting hairs but I found it interesting that a 15W would flow better than a 10W in the cold. Living in Ohio and finding a few days to ride in the winter I may opt for the 15W50 when I run out of the Castrol.

[kballowe]

It’s raining and I was bored so was looking at oil specs. As you know MG recommends Agip/Eni 10W60 for many of our bikes. I’ve been using Valvoline Castrol Edge 10W60 because it is available locally though getting harder to find. ..........

Fixed it for ya

[Zenermaniac]

Oops!

[MMRanch]

That 20w50 looks like the best of both ends !    Thanks for putting them on  a graft for easy viewing ! 

[Wayne Orwig]

Geez, is it that time of year again?


 



 

[Old Jock]

Woo Hooo Oil Thread 

I'm having some difficulty with that chart AFAIK the W stands for Winter and is the viscosity equivalent at 0C.

Yet the 10W grades have a higher viscosity than the 15W at 0C

It's always better to look at Spec sheets for the oils you're considering and make a back to back comparison as the values vary considerably and oils at a given grade can vary quite considerably, VI should also be looked at as the higher the number the less sensitve the viscosity is to temperature changes

Example on the spec sheets I've got to hand here are 3 viscosities all for 10W/60 oils

40C    103.1    178.0  160.1
100C    22.46   25.6     23.9

Viscosity calculators can be wildly inaccurate, especially when extrapolating values, as they're normally assuming a monograde and multigrades do not behave in the same way. Not saying they're not useful, just don't believe the results are cast in stone.

I use a calculator based on the Walther correlation and using it just to check the Eni at 0C it returned a value very close to the chart only differing by a few decimal places at 1623.41

[Zenermaniac]

Woo Hooo Oil Thread 

I'm having some difficulty with that chart AFAIK the W stands for Winter and is the viscosity equivalent at 0C.

Yet the 10W grades have a higher viscosity than the 15W at 0C

It's always better to look at Spec sheets for the oils you're considering and make a back to back comparison as the values vary considerably and oils at a given grade can vary quite considerably, VI should also be looked at as the higher the number the less sensitve the viscosity is to temperature changes

Example on the spec sheets I've got to hand here are 3 viscosities all for 10W/60 oils

40C    103.1    178.0  160.1
100C    22.46   25.6     23.9

Viscosity calculators can be wildly inaccurate, especially when extrapolating values, as they're normally assuming a monograde and multigrades do not behave in the same way. Not saying they're not useful, just don't believe the results are cast in stone.

I use a calculator based on the Walther correlation and using it just to check the Eni at 0C it returned a value very close to the chart only differing by a few decimal places at 1623.41

The Widman calculator DOES use multi grade points at 40C and 100C which I pulled from manufacturer reports and I’ve found the calculator to be reasonably close for comparison. Personally I’m not concerned with decimal points. Through the years much to my wife’s dismay I’ve put a lot of oil samples in the refrigerator and the freezer just to actually see the differences in cold flow. Yes, a thick oil can flow better than a thin in some brands. Each viscosity rating is actually a range of values, as you know, but the dividing line between them seems a little fluid (pun intended) between manufacturers. Even more so with gear oils. I’m interested in ratings in low temps because I ride occasionally in the winter and cold starting can be a real strain on the starter, electrical system, and  oil pump as well as possible engine wear before the oil gets flowing.

[Old Jock]

Interesting and agree, that checking some of the intermediate values can throw up unexpected results.

The Walther calculator also uses the 2 viscosity points and calculates results based on a double exponential function.

AFAIK the formula was derived on tests conducted on monograde oils, therefore its accuracy is strictly only applicable to monogrades, but it's better than nothing to determine interpolated or extrapolated values of multigrades. I assume that the higher the VI the less accurate it's going to be (i.e. it'll be more accurate with a 20/40 than a 10/60)

Your Widman Calculator appears to use a similar formula as the results from both return high correlation. I agree that decimals are pointless I posted the calculated result to illustrate how close my computed result was in comparison to your's

The paper I extracted the formula from can be found here (if you're interested)
https://www.doria.fi/handle/10024/177814

As you can see from my earlier post the first of the oil spec viscosities for 10/60 I posted has a markedly low viscosity at 40C in comparison to the others. That's Royal Purple XPR 10/60 which here in the UK is ridiculously expensive, but has a high VI.

My reason for delving into this was high temp and low pressure on a HiCam engine which I now run on a 10/60 and providing I'm not in traffic is great (but get it in traffic and it'll roast both itself and the rider)

Good Luck

John
 

[Zenermaniac]

The paper I extracted the formula from can be found here (if you're interested)
https://www.doria.fi/handle/10024/177814

John

Interesting reading, thanks.