I am wanting to find out how to calculate an oil's viscosity when mixing two different viscosities. For instance, 2 qts of 20w50 and 1 qt of straight 60 weight. I have my reasons for this.
Goofy question!
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Originally Posted By: porkchop01
I am wanting to find out how to calculate an oil's viscosity when mixing two different viscosities. For instance, 2 qts of 20w50 and 1 qt of straight 60 weight. I have my reasons for this.
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
Now, the FIRST NUMBER has NOTHING TO DO with the sercond. Your "Kinematic Viscosity" would be "53" but it would have a higher resistance to flow, cold.
I can respect the reasoning.
I am wanting to find out how to calculate an oil's viscosity when mixing two different viscosities. For instance, 2 qts of 20w50 and 1 qt of straight 60 weight. I have my reasons for this.
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
Now, the FIRST NUMBER has NOTHING TO DO with the sercond. Your "Kinematic Viscosity" would be "53" but it would have a higher resistance to flow, cold.
I can respect the reasoning.
Originally Posted By: HangerHarley
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
By doing this, you have made this one quart of straight 60 appear as 0w-60, which is not true.
But I agree, that first number has nothing to do with viscosity, so it doesn't make sense to even think of it in this case, but if we were to follow your logic, we would probably have been better of treating it as 60w-60, not 0w-60.
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
By doing this, you have made this one quart of straight 60 appear as 0w-60, which is not true.
But I agree, that first number has nothing to do with viscosity, so it doesn't make sense to even think of it in this case, but if we were to follow your logic, we would probably have been better of treating it as 60w-60, not 0w-60.
Originally Posted By: HangerHarley
Originally Posted By: porkchop01
I am wanting to find out how to calculate an oil's viscosity when mixing two different viscosities. For instance, 2 qts of 20w50 and 1 qt of straight 60 weight. I have my reasons for this.
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
Now, the FIRST NUMBER has NOTHING TO DO with the sercond. Your "Kinematic Viscosity" would be "53" but it would have a higher resistance to flow, cold.
I can respect the reasoning.
Shouldnt the first number go up as well with the straight weight oil beeing added? Just pondering this idea with my TC88.
Originally Posted By: porkchop01
I am wanting to find out how to calculate an oil's viscosity when mixing two different viscosities. For instance, 2 qts of 20w50 and 1 qt of straight 60 weight. I have my reasons for this.
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
Now, the FIRST NUMBER has NOTHING TO DO with the sercond. Your "Kinematic Viscosity" would be "53" but it would have a higher resistance to flow, cold.
I can respect the reasoning.
Shouldnt the first number go up as well with the straight weight oil beeing added? Just pondering this idea with my TC88.
Last edited:
After a short search, I found this:
https://bobistheoilguy.com/forums/threads/viscosity-index-calculator.89545/
and it had a link to this:
http://www.truckersoilforum.com/vicalc/VI.htm
You can not just add up and average weights, you need to use logs.
https://bobistheoilguy.com/forums/threads/viscosity-index-calculator.89545/
and it had a link to this:
http://www.truckersoilforum.com/vicalc/VI.htm
You can not just add up and average weights, you need to use logs.
Last edited:
Originally Posted By: Quattro Pete
Originally Posted By: HangerHarley
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
By doing this, you have made this one quart of straight 60 appear as 0w-60, which is not true.
But I agree, that first number has nothing to do with viscosity, so it doesn't make sense to even think of it in this case, but if we were to follow your logic, we would probably have been better of treating it as 60w-60, not 0w-60.
Now the light just came on,I think i get it now.
Originally Posted By: HangerHarley
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
Thats 40W-160.
Divide by three, its 13.3W-53.
By doing this, you have made this one quart of straight 60 appear as 0w-60, which is not true.
But I agree, that first number has nothing to do with viscosity, so it doesn't make sense to even think of it in this case, but if we were to follow your logic, we would probably have been better of treating it as 60w-60, not 0w-60.
Now the light just came on,I think i get it now.
Originally Posted By: Quattro Pete
Originally Posted By: HangerHarley
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
+1
33.3W-53
But oil
Thats 40W-160.
Divide by three, its 13.3W-53.
By doing this, you have made this one quart of straight 60 appear as 0w-60, which is not true.
But I agree, that first number has nothing to do with viscosity, so it doesn't make sense to even think of it in this case, but if we were to follow your logic, we would probably have been better of treating it as 60w-60, not 0w-60.
+1
33.3W-53 would be the logical average, but oils are rounded off or to be more acurate clasified into groups acording to a certain range (a certain range is a 0, 5,10,20,30,40,50,60,exc)
So one would have to look up the viscosity at 40 and 100 C for both oils and average them and then fine out what those averages fell into.
Originally Posted By: HangerHarley
Simple addition and division should do it.
Say you have 3 quarts.
20 50 +
20 50
and a third quart, 60 with no W number.
+1
33.3W-53
But oil
Thats 40W-160.
Divide by three, its 13.3W-53.
By doing this, you have made this one quart of straight 60 appear as 0w-60, which is not true.
But I agree, that first number has nothing to do with viscosity, so it doesn't make sense to even think of it in this case, but if we were to follow your logic, we would probably have been better of treating it as 60w-60, not 0w-60.
+1
33.3W-53 would be the logical average, but oils are rounded off or to be more acurate clasified into groups acording to a certain range (a certain range is a 0, 5,10,20,30,40,50,60,exc)
So one would have to look up the viscosity at 40 and 100 C for both oils and average them and then fine out what those averages fell into.
Originally Posted By: Ursae_Majoris
After a short search, I found this:
https://bobistheoilguy.com/forums/threads/viscosity-index-calculator.89545/
and it had a link to this:
http://www.truckersoilforum.com/vicalc/VI.htm
You can not just add up weights, you need to use logs.
That link dont work, all i get is a blank page.
After a short search, I found this:
https://bobistheoilguy.com/forums/threads/viscosity-index-calculator.89545/
and it had a link to this:
http://www.truckersoilforum.com/vicalc/VI.htm
You can not just add up weights, you need to use logs.
That link dont work, all i get is a blank page.
Works for me, just tried it. Do you have Java enabled?
Last edited:
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