Do thinner oils (SAE xW-20, xW-30) do better at high RPMs?

It was also mentioned about flow equaling lubrication in this thread. so I maybe had some questions about how critical oil pressure would be at these higher RPMs.

Seems they would matter more at the higher RPMs than anything, the oil pressures, rather than at idle or easy driving... Correct?

I also thought I read somewhere that Subaru has some sort of low output oil pump that could put out a max of 42psi. Or am I off the mark there or does anybody know what I am talking about?
All the oil pressure tells you is that you have X flow of oil in a Y resistance oiling system at the point of the oil pressure sensor. Journal bearing will flow a bit more oil with higher oil pressure (on top of what they naturally flow from PRM), which may help keep the delta-t of the oil coming out the sides down ... but higher oil pressure really isn't going to "lubricate" the bearing any better.
 
What made you go with getting the 2.0?? Wouldn’t the 2.5 be a stronger engine according to your post above that the EJ25 is just a larger EJ20 that would tell me that the EJ25 would be the motor you want. When you first mentioned going to this smaller displacement engine I assumed it was one of those super hot screamers that would spank your current one.
Well, after reading about the ej25 and coming from an H6 it seems that the ej25 actually kind of sucks and that's mostly because the walls between the cylinder and the coolant jacket are thin to make up for that extra displacement.

So when my ej25 started doing things that a cheaply purchased somewhat high mileage used engine that sat around for a long time would start to do.. I decided to get the car serviced and just use the other one (Taurus) until that got straightened out.

Not only that but it was cheaper than all the ej25s. Go on car-part.com they get like $1,000 for a low miles ej25
 
One thing I am curious about and I hope the Subaru people can provide more information on is that I read somewhere or saw something that one of these engines has an oil pump that basically puts out 42 PSI no matter what. Or 42psi max or something.

Maybe I'm misread and maybe it wasn't applicable to the Subaru but if anyone knows about that can they chime in?

As to the oil pressure versus flow thing, not sure if that was a serious post but I'm thinking maybe it was facetious because I think that lubrication is a function of both pressure and flow, oil needs to be pressurized to get through its boundary lubrication areas but flow is a result and it's somewhere within there that the engine is actually lubricated. Of course if I'm wrong about that please chime in.
 
If "pressure" lubricated engines manufacturers would recommend 90 wt.
Pressure does not lubricate an engine.
But you said "Flow=lubrication" in post #10. Oil pressure does correlate to oil flow through a flow restrictive oiling system.
 
Air cooled ... so they need thicker oil for that factor.
I was going to say.. Harleys etc or motorcycles I thought they had the thick motor oil to deal with all the heat and the way that they're on the bike.
 
One thing I am curious about and I hope the Subaru people can provide more information on is that I read somewhere or saw something that one of these engines has an oil pump that basically puts out 42 PSI no matter what. Or 42psi max or something.

Maybe I'm misread and maybe it wasn't applicable to the Subaru but if anyone knows about that can they chime in?
Most Subaru engines seem to have a high flow oil pump, and pretty high set pressure relief valve on the pump from what I've read from the Subaru guys here.

As to the oil pressure versus flow thing, not sure if that was a serious post but I'm thinking maybe it was facetious because I think that lubrication is a function of both pressure and flow, oil needs to be pressurized to get through its boundary lubrication areas but flow is a result and it's somewhere within there that the engine is actually lubricated. Of course if I'm wrong about that please chime in.
All you need for "lubrication" is the proper amount of oil between the parts. Oil volume is forced through the restrictive oiling system by the PD pump, and that causes "oil pressure". The oil pressure of the oil coming out the sides of a journal bearing is zero. Journal bearings just need an adequate supply of oil in order to hydrodynamically lubricate themselves through rotation. Higher oil pressure will help bearings "flow" more oil through them, but all you need is just enough oil supply pressure to ensure an adequate supply of oil volume to all parts of the engine.
 
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I was going to say.. Harleys etc or motorcycles I thought they had the thick motor oil to deal with all the heat and the way that they're on the bike.
Water cooled high revving motorcycles need 10W-40 to 20W-50 ... been that way for decades.

My Hayabusa makes 175 HP (stock) and revs to 11,000 RPM ... doubt it would like xW-30 or less viscosity for very long. Well, maybe if I kept it below 5,000 RPM ... impossible to do. :)
 
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Do they work harder with thick vs thin?

An engine will burn a bit more fuel to pump a heavier lubricant, which in turn results in the engine heating up a bit faster (a good thing, all things considered), but that fuel consumed is the reason that OEM's are chasing thinner and thinner oils, as the gains are primarily in short trip scenarios where engines are the least efficient in terms of operation. In steady state modes like highway cruising where the oil gets up to temp, the difference borders on immeasurable and in most cases likely is immeasurable outside a lab.

Of course all oils thicken as the temperature drops, so there is an advantage in terms of lower pumping losses if the lubricant starts out thinner. That said, an engine pumping 0w-20 at -20C is working a lot harder to move that oil than one pumping 5w-40 at 0C, so there is some relativity there. A popular adage on here has been "as thin as possible, as thick as necessary" which I think does a good job conveying the sentiment. If you are going to be spinning your rig to the moon or towing a trailer, this may warrant a more viscous lubricant than if you are doing runs to the corner store in Anchorage in February. Similarly, if you don't break 65 and drive like there's an egg under the pedal, you can probably safely use the thinnest grade allowed in the manual without a second thought.
 
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