10w40 vs 20w50 for track use
Jun 7, 2016, 11:46 AM
#16
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A friend just sent me a link to some recent oil testing:
https://540ratblog.wordpress.com/
It's super long but eventually gets to some interesting results.
https://540ratblog.wordpress.com/
It's super long but eventually gets to some interesting results.
http://www.bobistheoilguy.com/forums...pics/3120982/1
Its good data but I wouldn't consider it the "holy grail", just another set of data.
Although the high volume pump and lower weight oil really has me thinking about changing from 20W-50 VR-1, even on a built engine.
Jun 7, 2016, 11:49 AM
#17
So if I'm reading this right, viscosity does not equal film strength. Higher viscosity doesn't support bearing better than lower because it's thicker. The old adage of needing 15-50 to support stub shafts on cars without balance shafts isn't based on engineering but handed down "hey, this works".
Am I getting this right? Is viscosity determined by oil passage size then? This is all breaking down what I previously assumed to be correct.
Am I getting this right? Is viscosity determined by oil passage size then? This is all breaking down what I previously assumed to be correct.
Jun 7, 2016, 12:33 PM
#19
The old theory (with some science to back it up) is that oil looses viscosity as it heats/wears/gets contaminated. Naturally right. So racing wears it the most since your sitting at such high heat/rpm levels for so long. Thus we always ran a higher weight oil because 50 when you start can be 30 when your done. And 30 when you start can be 20 or lower when your done.
These days however syn technology has upgraded said oils to resist this a LOT more, but I still run 50 weight because i've proven it works for 3 years of racing on 1 engine before I rebuilt it just cause the other parts wore before the metal did. Also ol Nathan went from 30 weight to 50 weight on amsoil dom because the lab results said to.
These days however syn technology has upgraded said oils to resist this a LOT more, but I still run 50 weight because i've proven it works for 3 years of racing on 1 engine before I rebuilt it just cause the other parts wore before the metal did. Also ol Nathan went from 30 weight to 50 weight on amsoil dom because the lab results said to.
Jun 7, 2016, 12:49 PM
#20
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As a sanity check I pulled some numbers from the report to see the correlation between viscosity and "Wear Protection Capability" for oils that had multiple viscosity listed:
Castrol GTX, API SN conventional
20W50 = 96514
5w30 = 95392
5w20 =95543
High mileage 5w30 = 91404
LAT Synthetic Racing Oil, API SM
20W50 = 87930
5w30 = 81800
0w20 = 57228
Royal Purple API SN synthetic
20W50 = 83487
5w30 = 84009
5w20 = 90434
Kendall GT-1 High Performance with liquid titanium, API SN conventional
20W50 = 83365
0w20 = 71385
Other than Royal Purple, it seems that oil viscosity does correlate with wear protection within a given brand. Just a quick observation, I am no expert.
Jun 7, 2016, 01:17 PM
#21
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The old theory (with some science to back it up) is that oil looses viscosity as it heats/wears/gets contaminated. Naturally right. So racing wears it the most since your sitting at such high heat/rpm levels for so long. Thus we always ran a higher weight oil because 50 when you start can be 30 when your done. And 30 when you start can be 20 or lower when your done.
These days however syn technology has upgraded said oils to resist this a LOT more, but I still run 50 weight because i've proven it works for 3 years of racing on 1 engine before I rebuilt it just cause the other parts wore before the metal did. Also ol Nathan went from 30 weight to 50 weight on amsoil dom because the lab results said to.
These days however syn technology has upgraded said oils to resist this a LOT more, but I still run 50 weight because i've proven it works for 3 years of racing on 1 engine before I rebuilt it just cause the other parts wore before the metal did. Also ol Nathan went from 30 weight to 50 weight on amsoil dom because the lab results said to.
Jun 7, 2016, 02:00 PM
#22
Here are some paragraphs to discuss viscosity.
Its all a lot of reading but does seem to bring up some great topic points weather they are to be believed or not. I don't see any info on viscosity break down though.
From some of his points, I could see a desire to run a thicker oil if oil supply issues are present. Thicker oil gives more time before a bearing pushes oil out, but no clue how much actual buffer that is.
Plain bearings, such as rod and main bearings, are lubricated by oil flow, not by oil pressure. Oil pressure is NOT what keeps these parts separated. Oil pressure serves only to supply the oil to the clearance between the bearings and the crankshaft journals. Those parts are kept apart by the incompressible hydrodynamic liquid oil wedge that is formed as the liquid oil is pulled in between the spinning parts. As long as sufficient oil is supplied by the necessary oil pressure mentioned above, no wear can occur. And the higher flow rate of thinner oil, supplies more oil volume to the main and rod bearings, which also helps ensure that the critical incompressible hydrodynamic liquid oil wedge is maintained.
Thinner oil will of course flow out from the bearing clearance quicker than thicker oil will. But, by making sure there is sufficient oil pressure as mentioned above, the oil supply will always stay ahead of the oil flowing out, which will maintain that critical incompressible hydrodynamic liquid oil wedge.
Thinner oil will of course flow out from the bearing clearance quicker than thicker oil will. But, by making sure there is sufficient oil pressure as mentioned above, the oil supply will always stay ahead of the oil flowing out, which will maintain that critical incompressible hydrodynamic liquid oil wedge.
• Oil flow is what carries heat away from internal engine components. Those engine components are DIRECTLY oil cooled, but only INdirectly water cooled. And better flowing thinner oil will keep critical engine components cooler because it carries heat away faster than slower flowing thicker oil can. This is especially important with plain main and rod bearings, since the flow of oil through the bearings is what cools them. If you run thicker oil than needed, you will drive up engine component temps.
• Thicker oils DO NOT automatically provide better wear protection than thinner oils, as some people mistakenly believe. Extensive “dynamic wear testing under load” of over 170 motor oils, has shown that the base oil and its additive package “as a whole”, with the primary emphasis on the additive package, which is what contains the extreme pressure anti-wear components, is what determines an oil’s wear protection capability, NOT its viscosity. In fact, the test data has shown that 5W20 oils can provide INCREDIBLE wear protection with over 120,000 psi load carrying capability/film strength/shear resistance, while 15W50 oils can sometimes only provide UNDESIRABLE wear protection with less than 60,000 psi. So, DO NOT use thicker oil under the assumption that it can provide better wear protection for our engines, because that is simply NOT TRUE.
Its all a lot of reading but does seem to bring up some great topic points weather they are to be believed or not. I don't see any info on viscosity break down though.
From some of his points, I could see a desire to run a thicker oil if oil supply issues are present. Thicker oil gives more time before a bearing pushes oil out, but no clue how much actual buffer that is.
Jun 7, 2016, 02:07 PM
#23
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Per what PA Dutch posted, it seems that the thicker oils within a manufacturers line provide better protection.
Yes, Brand X 0w20 may out perform Brand Y 20w50. But what you have to do is compare Brand X's 0w20 to Brand X's 20w50 (hoping they have similar additive packs).
Yes, Brand X 0w20 may out perform Brand Y 20w50. But what you have to do is compare Brand X's 0w20 to Brand X's 20w50 (hoping they have similar additive packs).
Jun 7, 2016, 02:55 PM
#24
what dallas j posted makes a lot of sense and is exactly correct. all about film strength.
I think the question the 20w50 guys are posing is, why not? and to that end, idk. engine builders often times only care about the sanctity of the engine itself, and can guarantee "protection" with thick *** oil. pumps on the other hand, will certainly have a much harder time.
I think the question the 20w50 guys are posing is, why not? and to that end, idk. engine builders often times only care about the sanctity of the engine itself, and can guarantee "protection" with thick *** oil. pumps on the other hand, will certainly have a much harder time.
Jun 8, 2016, 09:01 AM
#28
this is an extremely good thread posted on BITOG regarding this issue:
http://www.bobistheoilguy.com/forums...pics/2206204/1
the thing that stands out to me is that the oiling system is the issue more than the oil itself. thicker oil will create more pressure, which is good for the poor oiling system. I'm countering those myself with a kiggly HLA and a baffled oil pan and possibly a crank scraper as well.
one post also notes that Red Line's 5w30 flows more like a 40wt oil, something to consider
http://www.bobistheoilguy.com/forums...pics/2206204/1
the thing that stands out to me is that the oiling system is the issue more than the oil itself. thicker oil will create more pressure, which is good for the poor oiling system. I'm countering those myself with a kiggly HLA and a baffled oil pan and possibly a crank scraper as well.
one post also notes that Red Line's 5w30 flows more like a 40wt oil, something to consider
