oil pressure question!

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is it possible that an engine require a specific oil viscosity to maintain high enough oil pressure say from 750 rpm to say 8000?like if a user went from 5w30 dino oil to 5w20 synthetic oil is it possible that the minimum oil pressure was raised from say 750 to 1500 rpm?(to get same minimum required oil pressure engine require?
 
It's possible an oil that is too thin for the application wouldn't maintain adequate pressure at hot idle.

Cold idle and above idle speeds should provide adequate pressure unless things are really wrong.
 
Originally Posted By: yvon_la
its sad!its almost like the rpm range is too wide lol!


What do you mean? With a positive displacement (PD) oil pump, the oil pressure will be higher at any given RPM with thicker oil. As said above, if the oil is super thin when hot, the idle pressure will be lower, and the oil pressure will be a little lower at every engine RPM above idle. That's how the oil pressure will behave with a PD oil pump as the oil viscosity changes.
 
I don't know ,if I use my car as an exemple,it sound like the minimum required oil pressure is too low when I use thinner oil (I went from 10W30dino to 5w20 synthetic)but this happen only at low rpm ,im concerned because I do a lot of city driving so my car will see ton of 750 rpm (hot idle revolution)to say 2000 rpm.(wich is about where the harsh noisier stuff happen)I ll probably go to mobil again but I ll probably use delvac1 le5w30 wich should end up on the sweat spot.i wouldn't be concerned if I was doing lot of long stretch but the fact I mostly do city driving I don't like the ruckus my engine make from 750 to about 1750 rpm

ty for info guys!
 
Originally Posted By: yvon_la
I don't know ,if I use my car as an exemple,it sound like the minimum required oil pressure is too low when I use thinner oil (I went from 10W30dino to 5w20 synthetic)but this happen only at low rpm ,im concerned because I do a lot of city driving so my car will see ton of 750 rpm (hot idle revolution)to say 2000 rpm.(wich is about where the harsh noisier stuff happen)


What oil weight does the car manufacturer recommend?

Do you have a real (and accurate) oil pressure gauge, or just an oil pressure light in the car?
 
10w30 just a light !I use sound but having seen material property of magnesium I suspect its likely just the magnesium in the oil augmenting the engine noise!

question,are there oil that have totally gotten rid of zinc and replaced it with say magnesium?
 
Originally Posted By: yvon_la
10w30 just a light!


If your oil light is coming on or flickering at idle, then go back to 10W-30. 5W-20 is too thin for your engine ... stick with what the manufacturer recommends.
 
The rule of thumb is that 10 lbs for every 1000 RPM is adequate. Put a real OP gauge on the engine and see what you're actually getting. Idiot lights are next to useless.
 
Originally Posted By: RF Overlord
The rule of thumb is that 10 lbs for every 1000 RPM is adequate.


You forgot to add "for an American smallblock"...
 
Every auto engine has minimun test oil pressure spec's, one at low rpm and another at a specific higher rpm when the engine is up to temperature.
The spec's are in the workshop manual which may be on line. Some manufacturers also give an oil temp' at which the test should be taken for greater accuracy.
The most important and reliable is the OP at a specific higher rpm.

The first thing to check is that your idle speed is not set too low.
Sometimes the oil light is coming on simply because the idle speed is set too low.
If that's not the problem then get your OP tested, it's very easy to do.
 
rf:is there a way to have an idea of the pressure I should expect by looking at voa here?
like if viscosity index is at 12 can I expect around 10 psi per 1000 (approximation)no the light isn't coming on,i am just using my hearing to evaluate this.
 
Originally Posted By: yvon_la
rf:is there a way to have an idea of the pressure I should expect by looking at voa here?
like if viscosity index is at 12 can I expect around 10 psi per 1000 (approximation)no the light isn't coming on,i am just using my hearing to evaluate this.

No.
And when you say viscosity index you mean a KV100 of 12cSt I presume. Well the answer is still no.
And your hearing isn't going to help you either.

Get your OP tested and if you are running a heavier than spec' KV100 12cSt oil it should be well above the test spec's.
 
Originally Posted By: Shannow
Originally Posted By: RF Overlord
The rule of thumb is that 10 lbs for every 1000 RPM is adequate.


You forgot to add "for an American smallblock"...
Yeah, I suppose you're right, there...283 Chevy...350 Buick...289 Ford...those were the days.
 
Bonjour Yvon, moi souvenir, la belle PQ Just for fun log on the Nissan site in Africa and Australia and see what the oil recommendations are for your car there. Also try racing sites where young people are into drifting and street racing. Some of your ideas are hard to understand on Anglais web site. Go Habs!
 
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