Thick vs. Thin

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You're incredible, without ever rethinking or answering anything you need to stray away by all means, here to the galleries, but when "looking" at the gallery content you again don't read what they note: Said differences for them were "no statistically significant differences" in that regard. Did I get that wrong? Not necessarily taking my time reading up since

I of course had been referencing very different aspects when finding this for the pushrod-lifter-rocker route we'd been coming from. Never been talking about faults of PD pumps either by the way. So, what ragged edges? Your ideas are all too well known, they must have been flooding the forum for ...50 years?
What are you actually talking about? The oil pumpability study you're latching on to with some claim that PD oil pumps don't do what I say is out of context. In other words, go back and read what I've said. A PD oil pump can not operate correctly if the oil can't adequately flow into the inlet side of the oil pump. That is the "pumpability" factor of the oil. The study is focus on the pumpability of different oils, not the operation of the PD oil pump. If every one of those oils was much warmer and not on the "ragged edge" of being adequately pumpable or not, you'd see there would be no time differences worth mentioning between them.

Again, please explain why Oil G and Oil R pump just fine ... since the PD is obviously doing it's job very well just as it was designed to do. Once you realize why those oils pumped very well, then you'll understand that those oils that don't build pressure well is the fault of the oil not being very pumpable, and not the fault of the PD oil pump.

What is the correct "W" rating for the conditions from now on? Differences between 5W-40 and 10W-30 for just -15°C in testing had been better but not good enough to accept the findings. Are the measurable delays even for these deemed explained on the suction side?
Correct such oils should be down to -25°C and below.
The study is comparing different oil formulations. Obviously, they don't all pump the same through the same engine with the same PD pump. This study is 50 years old, so who really knows what kind of VII additives, etc were used in each of these oils. Maybe you should try to find a similar study with way more modern oil formulations.

Table 3 again illustrated the problem, and there's 14 pages to skim in case of interest: What are your slow oils doing in lifters and pushrods for three out of five minutes when it takes them half as long to get to the lifters? Findings like these that are common, pressure sensors on engines therefore get relocated from a near end on an easier bank to the far end on the more difficult bank for example. Watching blobs of the pudding appear at one end much earlier than at the other illustrates the lack of positive displacement distribution, similar interest provided....
Sounds like an engine design problem to me. Oils G and R are obviously producing adequate oil pressure pretty darn fast for oil at -20F. Not the PD pumps problem that oil won't make it to other parts. How long did it take Oil G and Oil R to reach those pushrods and lifters? The oils that are "slow" to get there are slow because they just aren't pumpable. If the oil is slow to get to the pushrods and lifters, then it's slow to get to every part of the engine because .... wait for it ... it's not adequately pumpable.

Perfectly fine to never be interested, but you're ideas are not reflected by the findings and so some poor hypothetical other guy that missed the other thread may still see and read it here the way they noted them. Let's let him give the MC professor my regards :) He could even point Project Farm to persistant video demand in that regard – till the day you start explaining where and how your ideas were ...developed.
IMO, your not seeing what was actually happening in that study and don't understand why some oils pump fine and others don't in the same engine with the same PD pump. I've tried to explain it, buy you're not seeing the fact that the way the oil is pumped and sent through the engine is because some of those oils are simply not very pumpable at -20F. Simple as that - and the fact that Oil G and R pumped fine backs up the fact that some of those oils are not very pumpable. I doubt "Mr. MC Professor" would understand either since he believes that oil jets just won't function correctly with just a one grade change in motor oil, lol.

Bottom line, if someone uses their vehicle in very cold climates and don't want sluggish oil distribution throughout the engine, then use an oil viscosity appropriate for the the cold climate they are in.
 
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Staff for "moderators" and administrators is acceptable? I really thought so.
His troops (and similar), well, you'd need to see and read for yourself. Not counting them ;-) And missing their graphic disapprovals.
 
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Sowieso. Not the beer, but he's never reading or interested, so more absence means better reading for me.
 
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Same problems here, ZeeO? On the edge @-15°C twenty years ago? Cheap recycling, you may have seen it somewhere.
I can try to shoot alternative data. Anything's becoming more interesting for the nights.


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Sowieso. Not the beer, but he's never reading or interested, so more absence means better reading for me.
If you're refereing to me ... I am reading and interested. If I wasn't, I wouldn't have made it this far in the discussion.

Same problems here, ZeeO? On the edge @-15°C twenty years ago? Cheap recycling, you may have seen it somewhere.
I can try to shoot alternative data. Anything's becoming more interesting for the nights.


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Like I said before, these tests are being done on real engines with a PD oil pump with a pressure relief valve. How much of the increase in time to get proper oil pressure rise or oil to a certain location in the engine is due to the PD pump pressure relief valve opening to some degree when the oil is so cold and thick? ... which would obviously cause some lack of flow volume to the oiling system. Or how much of what you see is due to specific engine design? You do realize that can be part of the reason we see what these studies show. And I'm betting these tests were done with essentially dry galleries, and not on engines that have been ran and have galleries full of oil before the cold start - like a real engine in use on the streets like we own here would have. Another thing that may be apples-to-oranges context.

The real test would be to test only a PD pump (without an active pressure relief valve) under these same conditions with an adequate inlet system to minimize oil pumpability factors on the inlet side, and measure the inlet vs outlet flow rates to see how they may change pumping efficiency as a function of viscosity. But these test using real engines only defines how that specific engine using those specific oils behaves at those specific temperatures, and their sensitivity to oil pumpability and oiling system distribution at super cold temperatures. There are many other factors involved causing these results beside the performance of the stand-alone PD pump.
 
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There is a reason a PD oil pump is are used in an engine.

Note this PD pump characteristic from the linked article:
"As the fluid becomes more viscous, is gets harder for the fluid to slip between the clearances in the pump and increases the volumetric efficiency. The efficiency of PD pumps is not as dramatically affected by changing conditions as centrifugal pumps are."


Pump efficiency performance vs viscosity shown below. So with cold thick oil, the PD is the most efficient at pumping. But when oil pumpability, pump pressure relief and various engine design factors come into play, you can get oiling system behaviors like shown in the "time to pressure" studies. If the pump can get oil volume into the inlet effectively, it will push basically that same volume of oil out the outlet - that's the sole design characteristic and purpose of a PD pump. What happens downstream of that is effected by the oiling system design and how close the cold oil is to the lack of pumpability.

ZeeOSix said:
The real test would be to test only a PD pump (without an active pressure relief valve) under these same conditions with an adequate inlet system to minimize oil pumpability factors on the inlet side, and measure the inlet vs outlet flow rates to see how they may change pumping efficiency as a function of viscosity.

oil pumps - flow rate viscosity.png
 
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Didn't I say just that here and over there: That PD is somewhat meaningful for the characterization of the pump itself but rather meaningless for our focus? Yes, that's been me.
Could you try a forum search on "positive displacement pump" to find out, how many people whose questions and topoi in recent years got "answered" with these issues this treatment may have actually been interested in pump tests instead of lubrication? Probably not.
 
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I just can't see 10w oils being that bad even in colder temperatures down to at least 0F. I know 5w oils have been around for a long time but they weren't used excessively until the 1980's. It wasn't extremely uncommon to see engines with 200K+ miles in the late '60's through the '70's when nearly everyone used 10w30 or 10w40. I'm still using 10w40 year around in all my cars with no noticeable issues. I'm not in the coldest area of the US but I'm far from being in the warmest.

Multi-weight oils like 5W-30 have been available since the early 1960's. And 5W-20 was recommended for some GM engines as a winter oil in the 60's.
 
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Didn't I say just that here and over there: That PD is somewhat meaningful for the characterization of the pump itself but rather meaningless for our focus? Yes, that's been me.
Could you try a forum search on "positive displacement pump" to find out, how many people whose questions and topoi in recent years got "answered" with these issues this treatment may have actually been interested in pump tests instead of lubrication? Probably not.
There are a lot of people who don't understand how PD pumps and engine oiling systems work ... so it never hurts to visit PD pump operation. But you are focused on PD pumps throughout these discussions - started way back in your post #37 - HERE

Back to the "topic", whatever that really is anymore since it's been going in circles, lol. Let me ask you a few questions.

1) If the oil pumpability and PD pump performance isn't lacking, and the pump pressure relief never operates (no pressure relief happening), what do you think is the reason for the increased times for oil to get to pressure or to various engine locations? You just post tables and say nothing about why you think is happening.

2) If 3 GPM of oil leaves the oil pump and goes into the oiling system, then by definition 3 GPM of oil must be distributed throughout the oiling system. So, it seems your claim is that certain circuits of the oiling system are going to have huge changes in flow and the time it takes to obtain oil pressure - but how can that happen if the flow volume has not been decreased?

3) You seem to think - just like "MC Professor" - that even a small change in oil viscosity being supplied by a PD pump is going to drastically change the flow to only certain branches of an oiling system - like piston cooling jets. Can you find a study that shows the various changes in flow to each oiling branch of an engine if the flow volume remains constant, but the oil viscosity changes?

4) Can you snip and post from those study papers showing that: a) The pump pressure relief valve was not operating at all, and b) If the oil galleries in those engines were all dry or all still full of oil before the cold start-up.
 
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Same mistake over and over... Oil is forced out the pump (first eventuality of relief aside) into the distributive ;-) system like blood being forced into the first available large artery. From there no flow through individual branches anywhere is guaranteed, not in the engine, not in the Adonis.
"PD" is characterizing a pump and nothing but a pump, never a distribution from there. Even fifty percent more positive D would only characterize a pump, not a distribution, unless individual elements...

Da capo.
Hi Blingo,

Where would the pumped oil go? it's thick and won't like being pushed out of clearances. The galleries are the path of least resistance until they are all full of viscous oil. Only if clearances are very large and galleries long and narrow would there be significant oil leakage before the galleries are full.
 
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Hi Jetronic, let's not be formal, let's become fiercely focused :)

Usually pressure drop along a (main) gallery won't be dominant in my view. Galleries in relation to what they're aimed at should be more like a pipeline, almost like a plenum – but this also means they'd be more like this path of least resistance when the oil has a choice of finally making it to and through a first or second bearing or making it farther through the gallery to a last or second last quasi competing bearing instead that's also awaiting. A certain pressure may be quickly seen at a first bearing, further pressurization there will depend on the pressure buildup along the gallery.

Before the same pressure level makes it into the fifth bearing the entrainment at the first bearing has become one path of less resistance in relation to the fifth, that's for only one sort of points of lubrication run from one gallery (don't know if the 56 cylinder could have seven or 14 such in parallel for just one sort of lubrication points ;-(
Meanwhile other lubrication points or else will have begun releasing blobs of the pudding aiding further delay of total and local pressure rises. Blobs onto a timing gear, relief off a pressure regulator,.. even cooling jets maybe where not controlled by a thermal pellet or so. The total is always a cold vulcano while warming up.

Now, if I may come back to the heads, the pushrods and the lifters we started with: Regarding the rockers of course their pushods are rather narrow little galleries (or channels at least) (just to not even try to follow those other guys into the lifters feeding these gallods).
Next to everything else in an engine will have tendencies of becoming paths of less resistance in relation to these rockers. That's what the tables are showing and Project Farms are filming for us.
A last camshaft bearing may also be worse off than a first main bearing. And so on. Not much statics for these first minutes.
 
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I was poking around Valvolines website and ran across this in the FAQ.

“Is it ok to use 5W-30 in a car if the owner's manual calls for 5W-20?

Valvoline does not recommend doing this. Using a heavier grade than recommended may cause decrease in fuel economy, higher engine loads and eventually shortened engine life. Using a lighter grade than recommended may result in excessive mechanical wear and reduced engine life. For maximum engine performance, follow the recommended motor oil viscosity and maintenance schedule provided in your vehicle's owner's manual.”

Higher engine load and leading to shorter engine life with thicker oil vs excessive mechanical failure with thinner oil. Did not really get a straight answer from Valvoline. 🤦‍♂️

I guess the age old debate will never be settled. I can picture Bob Uecker beer commercials (Taste great vs. less filling). That just made me thirsty 🍺.
I remember years back when Castrol was still recommending their 20w50 despite owner manuals saying 5w.
 
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