Does thickness of the oil matter on a performance application?

No engine is "built" for a certain grade.
When it comes to blueprinted performance engine builds, yes there are.

In engine building, "loose" engines generally make more power, "loose" meaning larger bearing clearances. Engine builders often will build to specific clearances and recommend a viscosity to match that engine build, choosing thicker when building looser.
 
No engine is "built" for a certain grade.
When it comes to blueprinted performance engine builds, yes there are.

In engine building, "loose" engines generally make more power, "loose" meaning larger bearing clearances. Engine builders often will build to specific clearances and recommend a viscosity to match that engine build, choosing thicker when building looser.
I dont think that is what was being said.......

In other words, one does not start off the build thinking: "well I am going to build an engine specifically for a 40wt oil." An oil is used to accomodate a circumstance, not the other way around.
 
I dont think that is what was being said.......

In other words, one does not start off the build thinking: "well I am going to build an engine specifically for a 40wt oil." An oil is used to accomodate a circumstance, not the other way around.
Ok, then even so I disagree. We're seeing this on the OE side where 0W-8 is being engineered around in engine design, with main bearings growing larger to increase surface area and accommodate lower MOFT.
 
Ok, then even so I disagree. We're seeing this on the OE side where 0W-8 is being engineered around in engine design, with main bearings growing larger to increase surface area and accommodate lower MOFT.
You are talking two different things. OE is after CAFE, the discussion was about high power engines, built by engine builders, such as a local guy or the like.
 
You are talking two different things. OE is after CAFE, the discussion was about high power engines, built by engine builders, such as a local guy or the like.
I'm responding to the statement, "No engine is 'built' for a certain grade". I know I gave two different types of examples, but tell me how that makes the blanket statement of "No engine is 'built' for a certain grade" correct when clearly engines are being built to utilize a specific grade.
 
I'm responding to the statement, "No engine is 'built' for a certain grade". I know I gave two different types of examples, but tell me how that makes the blanket statement of "No engine is 'built' for a certain grade" correct when clearly engines are being built to utilize a specific grade.
The context from which the statement was made. It is not really a blanket, because of the context.
 
I'm responding to the statement, "No engine is 'built' for a certain grade". I know I gave two different types of examples, but tell me how that makes the blanket statement of "No engine is 'built' for a certain grade" correct when clearly engines are being built to utilize a specific grade.
I like the phrasing with respect to the 0W-8 situation as them being built to tolerate a certain grade (or grades). Because of course they'll work just fine on a heavier oil. Conventional engines of course do not tolerate oils that thin.

We see this with back-spec'ing as well where Toyota back-spec'd certain engines that were clearly designed with accommodations, to thinner oils. Ford did the same thing, engines that, when produced, were spec'd for 5W-30, but later back-spec'd to 5W-20.
 
Ok, then even so I disagree. We're seeing this on the OE side where 0W-8 is being engineered around in engine design, with main bearings growing larger to increase surface area and accommodate lower MOFT.
Built to tolerate without excessive wear under most conditions. But not built to require. A higher grade as the OP was asking will not damage.

When people say “built for” it implies something that’s not there.
 
I like the phrasing with respect to the 0W-8 situation as them being built to tolerate a certain grade (or grades). Because of course they'll work just fine on a heavier oil. Conventional engines of course do not tolerate oils that thin.

Ok so you guys are losing me here, I'm not near the oil guy you guys are.

I was under the impression that too thick of oil = spun bearings or wear. So apparently I had it backwards...Too THIN of oil (or lack of oil also) will wreck bearings?

"Of course they'll work just fine on a heavier oil" What do you mean? So are you telling me if a motor was spec'ed (lets not say "designed") with clearances that warrant a 10w40 weight oil, you are perfectly fine using 20w50?

***With the above being clear that 20w at cold start will be very thick and possibly not good*** (Why do you only see 20w50 and not something like 10w50?)
 
Ok so you guys are losing me here, I'm not near the oil guy you guys are.

I was under the impression that too thick of oil = spun bearings or wear. So apparently I had it backwards...Too THIN of oil (or lack of oil also) will wreck bearings?

"Of course they'll work just fine on a heavier oil" What do you mean? So are you telling me if a motor was spec'ed (lets not say "designed") with clearances that warrant a 10w40 weight oil, you are perfectly fine using 20w50?

***With the above being clear that 20w at cold start will be very thick and possibly not good*** (Why do you only see 20w50 and not something like 10w50?)
Yes. You can run 20W-50 in something that calls for 0W-20, nothing is going to get damaged unless the temp is too low and the oil doesn't pump. On the other hand, if you've got an engine that spec's like 5W-40 and you put 0W-8 in it, the odds of it tossing a rod through the side as a result of spinning a rod bearing are quite high.
 
Yes. You can run 20W-50 in something that calls for 0W-20, nothing is going to get damaged unless the temp is too low and the oil doesn't pump. On the other hand, if you've got an engine that spec's like 5W-40 and you put 0W-8 in it, the odds of it tossing a rod through the side as a result of spinning a rod bearing are quite high.

Because......You are going the other direction and running thin oil, right?
 
Yes. You can run 20W-50 in something that calls for 0W-20, nothing is going to get damaged unless the temp is too low and the oil doesn't pump. On the other hand, if you've got an engine that spec's like 5W-40 and you put 0W-8 in it, the odds of it tossing a rod through the side as a result of spinning a rod bearing are quite high.
I find it funny we have to go to extremes. 0w8, vs 20w50........same thing ,close enough.
 
so the higher contact area, the more bearing surface, the less need for higher viscosity?......but not necessarily less wear?
Yeah, you aren't reducing wear in other areas by going thinner, that's why DLC coatings and a greater focus has been put on the additive package. But of course the heavier oils benefit from these additive package upgrades too and would produce even less wear.
 
so the higher contact area, the more bearing surface, the less need for higher viscosity?......but not necessarily less wear?
The big end of the connecting rod is subject to tremendous force upon each combustion event. The oil flowing through the rod bearings is cushioning that blow, but with thinner oil film thickness (providing less cushion) you need to make the bearings wider to distribute that force along a larger area, because if the "cushion" of oil is both too thin and too small (in terms of area) then the rod bearings are going to make contact with the crank journals instead of riding on the hydrodynamic wedge of oil.
 
The big end of the connecting rod is subject to tremendous force upon each combustion event. The oil flowing through the rod bearings is cushioning that blow, but with thinner oil film thickness (providing less cushion) you need to make the bearings wider to distribute that force along a larger area, because if the "cushion" of oil is both too thin and too small (in terms of area) then the rod bearings are going to make contact with the crank journals instead of riding on the hydrodynamic wedge of oil.

So (to a point) heavier weight oil is better for internal parts on high stress situations it seems.

Again, curious why there are no 10w50 in common oils.

There's this https://drivenracingoil.com/i-30497868-gp-1-conventional-sae-50.html
 
The big end of the connecting rod is subject to tremendous force upon each combustion event. The oil flowing through the rod bearings is cushioning that blow, but with thinner oil film thickness (providing less cushion) you need to make the bearings wider to distribute that force along a larger area, because if the "cushion" of oil is both too thin and too small (in terms of area) then the rod bearings are going to make contact with the crank journals instead of riding on the hydrodynamic wedge of oil.
I wonder to what end?
 
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