Why I Switched to 0W8

RDY4WAR said:
They're also pounding that oil with ~8,500 psi bearing load at 8,500-10,500 rpm the entire time. After 40+ passes on some of those engines, the bearings are still in like-new condition. If the oil can withstand that load, without shearing, it'll certainly hold up in a commuter car that may see 3,000 psi bearing load at the very most at WOT,
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What is the oil temperature in these pro-stock cars when they leave the starting line? And what kind of oil pump volume and pressure oil pumps are they running? I'm betting the oil temperature is way below 212F and the oil pumps are not like in your everyday road car.
 
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ZeeOSix said:
What is the oil temperature in these pro-stock cars when they leave the starting line? And what kind of oil pump volume and pressure oil pumps are they running? I'm betting the oil temperature is way below 212F and the oil pumps are not like in your everyday road car.
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I recommend the teams heat the oil. Many do and have pads wrapped around the dry sump tanks. Based on SRV testing we know the COF gets better all the way to 300F. So not hot enough is the official answer. 60psi down the track and 20psi at idle. They will run a 5 stage pump. Windage is important, vacuum is important. The pumps stabilize the rings. Ring seal is everything.

So the good news is the road car will stand a better chance of taking advantage of some of the chemistry the race car cannot.
 
High Performance Lubricants said:
I recommend the teams heat the oil. Many do and have pads wrapped around the dry sump tanks. Based on SRV testing we know the COF gets better all the way to 300F. So not hot enough is the official answer. 60psi down the track and 20psi at idle. They will run a 5 stage pump. Windage is important, vacuum is important. The pumps stabilize the rings. Ring seal is everything.

So the good news is the road car will stand a better chance of taking advantage of some of the chemistry the race car cannot.
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But what is the actual oil temperature? ... the viscosity will be relative to the temperature. I highly doubt they get the oil to 100C with sump heater blankets. If it's well below 100C, then the viscosity is going to be thicker then the specified KV100. If it's only 120F (49C) then it's really more like a thicker oil at 212F (100C).
 
High Performance Lubricants said:
60psi down the track and 20psi at idle. They will run a 5 stage pump.
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Any idea on the flow volume while going down the track at max RPM. and the sump capacity? Relatively low oil pressure can be from the thinner oil and bearing clearances ... and low oil pressure doesn't mean the oil flow volume is also low.
 
They do not track the oil temperature. Keep in mind the blocks are chilled as cold as they can get them. The 10 quarts of oil will give up most of its heat to the block. I doubt it would get much beyond 130 F if at all. The bearing clearance is way larger than you would think. Tighter is not better. I’m not going to disclose the numbers. I will see if I can get the pump flow.
 
High Performance Lubricants said:
They do not track the oil temperature. Keep in mind the blocks are chilled as cold as they can get them. The 10 quarts of oil will give up most of its heat to the block. I doubt it would get much beyond 130 F if at all. The bearing clearance is way larger than you would think. Tighter is not better. I’m not going to disclose the numbers. I will see if I can get the pump flow.
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Yes, these cars aren't even close to an everyday road car, and all those things combined actually pushes them to run a thinner oil. I'm sure the oil volume going though the oiling system is pretty high at those RPM, and the increased oil volume helps keep (along with larger bearing clearances) the oil cooler inside the bearings. The sump temperature is essentially going to remain constant over the short run down the track.
 
ZeeOSix said:
Yes, these cars aren't even close to an everyday road car, and all those things combined actually pushes them to run a thinner oil. I'm sure the oil volume going though the oiling system is pretty high at those RPM, and the increased oil volume helps keep (along with larger bearing clearances) the oil cooler inside the bearings. The sump temperature is essentially going to remain constant over the short run down the track.
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All correct statements. And yes the pumps flow a ton.
 
RDY4WAR said:
They're also pounding that oil with ~8,500 psi bearing load at 8,500-10,500 rpm the entire time. After 40+ passes on some of those engines, the bearings are still in like-new condition. If the oil can withstand that load, without shearing, it'll certainly hold up in a commuter car that may see 3,000 psi bearing load at the very most at WOT,
A major factor in EHL oil film thickness is the roughness of the lubricated surfaces. Most all modern engines will have shallow and consistent honing and smooth crank journals. This allows a thinner oil film before reaching mixed and boundary lubrication. An engine built in the 1960s with poor crank alignment (by today's standards), rough hone work, big 5/64" and 3/16" rings, and soft babbitt bearings likely wouldn't last long with a 0W-8 oil regardless of the bearing clearance.




Fine, you talked me into it.
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Very good. You have a lot of knowledge and experience that is very interesting and educational to read.
 
billt460 said:
0W-8 in cold weather??? Not me. I'm going with Ronsonol or Zippo Lighter Fluid. Much better cold flow rate. And the heavy shearing will aid in combustion. Which helps in getting things warmed up in a hurry.
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Redline and Mobil 1 0w-40 has a pour point of -76°F that's about as thin as I'm going.
 
OVERKILL said:
I personally think it's an interesting experiment. It's a custom lube from a board sponsor, worst that's going to happen is that it blows up. If he's willing to take that risk, which he seems to be fine with, then who am I to chastise him for doing so? It's not like he's being grossly misled by the membership, he took on this exercise of his own volition.

We know this isn't going to be a highly controlled experiment with tear-down testing and measurements. UOA's of course aren't going to tell us much either. The takeaway will mostly be whether it blows up or not and that's fine I think.

It'll either be spectacularly boring, or there will be some fireworks. Guess we'll see :D
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It probably won't blow up, especially considering it's a hybrid which sees frequent duty cycling and is a series hybrid.
 
Rmay635703 said:
Also in that case the oil would tend to thicken, right?
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As the lighter fractions flash off? Potentially. But the base oils used are insanely light (hence the Noack) so you'd probably just end up with disappearing lube and the potential for significant deposits.
 
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