real world differences in flow rates

[gusgeds]

Hi,following on from recent posts can anyone tell me what real differences in flow rate between a 10/40 A3 oil and a 5/30 A3 oil at 0 centigrade and at -5 centigrade and even down to-10 centigrade please?
Thanks in advance

 

[Pablo]

A couple comments/questions. What do you mean by "flow rate"?

Also it really depends on the oil.

Here's Widman's J300 chart:

http://www.widman.biz/Seleccion/Viscosidad/SAE_J300/SAE_J300_English/sae_j300_english.html

If you can find it, reading the whole SAE J300 is a good starter course for motor oils. I have the latest, but I don't see it posted on the web for free.

 

[gusgeds]

Hi Pablo, i suppose what i am trying to get at is the difference in time to get oil to the valve gear at those different temps with oils being say the same semi synthetic spec the only difference being a 10/40 versus a 5/30 viscosity, i suspect it is not a really huge difference in real world conditions, thanks

 

[Gary Allan]

Well, there's not much you can do about it. If you are spec'd 10w-40 and you encounter 0C temps ..you get what you get.

So, you want to use the lowest acceptable visc fluid with the broadest viscosity index.

I can't tell you the difference in time, but it's easy to show the difference between two fluids of different VI.

http://www.widman.biz/Seleccion/Viscosidad/Conversiones/Graph/graph.html