Thick vs. Thin

Pennzoil motor oil
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gregk24 said:
Too thick and oil WILL cause issues, too thin an oil WILL cause issues. There is a middle ground. You can have an oil that will provide better fuel economy and better wear resistance upon cold start / short trips (thinner). You can also choose a thicker oil that will provide better wear protection during high load / high speed conditions. Lets be honest though, most of us are doing short trip driving to the grocery store and around town where thinner oils shine.
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Only if it’s too thick in cold conditions and cannot be pumped. Other than that, “thick” oil will not cause issues. What issues WILL it cause?
 
I generally prefer thinner oils if 0W-20/5W-20 are really that much thinner than a typical 5w30. But Valvoline is just ridiculous here. Using a 5w30 is not going to "shorten your engine life". It probably has no impact either way...
 
kschachn said:
What issues WILL it cause?
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According to Valvoline.
Not My Words.

“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.”
 
Drew7a said:
According to Valvoline.
Not My Words.

“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.”
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The first two? Sure. The third one? No way. Thicker oil can reduce wear, it doesn’t cause it.

Unless of course it is so thick and the temperature is so cold that it cannot be pumped. Then yes you’re going to have a problem with wear at that point. But then your real problem is an incorrect selection of a proper winter rating.
 
ka9mnx said:
"under extreme load conditions" whatever that means...
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I think it means that it's so subjective that a heavier oil can be used. Similar language is in my '15 manual, they've toned it down...pure CAFE phraseology, Toyota can only recommend the oil (0w-20) that was used for mpg testing.
 
simple_gifts said:
?

No oil company is going to vary from the mfg viscosity recommendation; why would they?

Legal position, not a technical one.
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Exactly. If they recommend anything different than the manufacturer then they would incur liability if you follow their advice and your engine blows up, even if it isn't an oil related failure.
 
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Dang, I planned to invent the word, but frictive already seems to be known in correct english ;-(
 
blingo said:
Probably especially great through pushrods heated the frictive route between lifters and rockers.
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heated ??

Been discussed many times ... positive displacement oil pump. As long as the oil is viscous enough to properly get to the pump (ie, "pumpability" which is part of the cold "W" rating by the SAE), then it will be forced through the oiling system regardless of viscosity.
 
Always a pleasure to advance the american English.

PD unfortunately does nothing for such a pushrod in -15°C, not even when the winter rating would be correct for -25°C or lower. Maybe you missed the latest PD sessions on here. Individual PD elements for each of course might do – six pushrods, six plungers. I guess I called that positive displacement distribution recently to advance the american English.

Being forced through the system doesn't necessarily mean through much of the system. Think of a strokes and coronaries ;-)

https://bobistheoilguy.com/forums/threads/motorcraft-university.336731/post-5652709
 
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blingo said:
Always a pleasure to advance the american English.

PD unfortunately does nothing for such a pushrod in -15°C, not even when the winter rating would be correct for -25°C or lower. Maybe you missed the latest PD sessions on here. Individual PD elements for each of course might do – six pushrods, six plungers. I guess I called that positive displacement distribution recently to advance the american English.

Being forced through the system doesn't necessarily mean through much of the system. Think of a strokes and coronaries ;-)

https://bobistheoilguy.com/forums/threads/motorcraft-university.336731/post-5652709
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What you're seeing is the "pumpability" difference into the pump's inlet side due to viscosity, and most likely due to the impact of the difference in viscosity on pump intake screen/tube and pump inlet. Once the oil makes it into the pump, the oil will be forced from the exit of the pump and through the oiling system. The oil that goes up through pushrods is forced and part of the PD pump force feed oiling system. Look at the difference between 5W, 10W and 15W. There's a much bitter delta between 5W and 15W than between 5W and 10W because at that temperature the 15W is starting to impact pumpabililty to a greater degree.
 
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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.
 
blingo said:
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.
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Rehashing this again. Increasing or decreasing the volume output of the PD will also increase or decrease flow pretty much proportionally in every branch of the oiling system. Even though a house water system isn't PD pump supplied, the same thing basically happens in your house water system or shower head (I know you love that analogy) if the supply pressure is increased or decreased. If the main water line supply pressure to your house suddenly decreased (and stayed constant regardless of flow out of it) you would see a corresponding proportional decrease in pressure/flow at every faucet in your house. If your house water system was PD pump supplied, it would ensure this even more.

That's the main reason PD pumps are used on engines ... to ensure all branches of the oiling system gets adequate oil all the way from idle to redline. If some branches didn't get adequate oiling due to cold thick oil (assuming the correct "W" rating is used), then you'd see all kinds of lack of lubrication damaged engines every winter ... but that just doesn't happen because the PD oil pump is still providing proper lubrication to all branches regardless of viscosity - as long as the oil can get from the sump into the pump adequately to start with (it's adequately "pumpable").
 
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