Oil Pressure Issue?

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I never understood this. I run 20-50 valv. When its 20 degrees out it pours like 90 weight, and when its a 100 out it pours like 30 weight how is this?
 
So far you've all missed the target so to speak about the viscosity ratings on Multi-weight Oils. Some are closer than others.
Years ago you had single weight oils, SAE 10, SAE 20, SAE 30...(you get the idea). The higher number the thicker the oil. Lower # for thinner oil. Thinner oils for winter & thicker (higher#)for summer. Along came the Multi-Weight oils, 10w-30, 20w-50, 5w-30 etc. The 1st # represents the oils viscosity characteristics in cold temp. It is a comparative #. So in other words a 10w-30 oil will flow like straight weight SAE 10 in cold weather. The 2nd # represents the oil's viscosity at higher temperatures. So again it's a comparative #. The same 10w-30 oil would flow like a straight weight SAE 30 at higher temperatures. 20w-50 flows like an SAE 20 in cold & an SAE 50 in warm temp.
It's like having 2 different grades available in your crankcase at the same time. Or you can think of it as bipolar if you like!
And the "W" does stand for WINTER.
The tests are done at specific temperatures for the higher # and the lower #. It doesn't directly mean weather the engine is warmed up or not.
So if you took 3 separate bottles of motor oil, SAE 10, SAE 10w-30 & SAE 30 and ran them all individually through a viscosity meter at the same temperature(say room temp) you'd get 3 different viscosity readings.
Have I confused the s**t outta everybody yet?
 
Lonewolf3165 said:
So far you've all missed the target so to speak about the viscosity ratings on Multi-weight Oils. Some are closer than others.
Years ago you had single weight oils, SAE 10, SAE 20, SAE 30...(you get the idea). The higher number the thicker the oil. Lower # for thinner oil. Thinner oils for winter & thicker (higher#)for summer. Along came the Multi-Weight oils, 10w-30, 20w-50, 5w-30 etc. The 1st # represents the oils viscosity characteristics in cold temp. It is a comparative #. So in other words a 10w-30 oil will flow like straight weight SAE 10 in cold weather. The 2nd # represents the oil's viscosity at higher temperatures. So again it's a comparative #. The same 10w-30 oil would flow like a straight weight SAE 30 at higher temperatures. 20w-50 flows like an SAE 20 in cold & an SAE 50 in warm temp.
It's like having 2 different grades available in your crankcase at the same time. Or you can think of it as bipolar if you like!
And the "W" does stand for WINTER.
The tests are done at specific temperatures for the higher # and the lower #. It doesn't directly mean weather the engine is warmed up or not.
So if you took 3 separate bottles of motor oil, SAE 10, SAE 10w-30 & SAE 30 and ran them all individually through a viscosity meter at the same temperature(say room temp) you'd get 3 different viscosity readings.
Have I confused the s**t outta everybody yet?
Click to expand...

Viscosity does not INCREASE with temperature, it DECREASES (gets thinner and pours easier...)

Have you ever tried to change the oil when the engine is cold???

What about when it's hot???

Does the oil drain faster when it's cold or hot??? :scratch:
 
Karl, what you are missing is this. Viscosity and thickness are two separate and distinctly different things.

Oil is thicker when cold. But its viscosity compared to when it is hot can certainly be less.
 
Lonewolf3165 said:
So far you've all missed the target so to speak about the viscosity ratings on Multi-weight Oils. Some are closer than others.
Years ago you had single weight oils, SAE 10, SAE 20, SAE 30...(you get the idea). The higher number the thicker the oil. Lower # for thinner oil. Thinner oils for winter & thicker (higher#)for summer. Along came the Multi-Weight oils, 10w-30, 20w-50, 5w-30 etc. The 1st # represents the oils viscosity characteristics in cold temp. It is a comparative #. So in other words a 10w-30 oil will flow like straight weight SAE 10 in cold weather. The 2nd # represents the oil's viscosity at higher temperatures. So again it's a comparative #. The same 10w-30 oil would flow like a straight weight SAE 30 at higher temperatures. 20w-50 flows like an SAE 20 in cold & an SAE 50 in warm temp.
It's like having 2 different grades available in your crankcase at the same time. Or you can think of it as bipolar if you like!
And the "W" does stand for WINTER.
The tests are done at specific temperatures for the higher # and the lower #. It doesn't directly mean weather the engine is warmed up or not.
So if you took 3 separate bottles of motor oil, SAE 10, SAE 10w-30 & SAE 30 and ran them all individually through a viscosity meter at the same temperature(say room temp) you'd get 3 different viscosity readings.
Have I confused the s**t outta everybody yet?
Click to expand...


We at least need to use the correct terms to start.

There is no such thing as oil WEIGHT. Oil is compared by GRADES. The American Petrolium Institue sets the standards on grades. The W stands for WINTER. Prior to WWII the chemicals to produce MULTI-GRADE oils was very expensive and not very reliable. That all changed after the war.

When I get a minute I will post the different grades and the temperatures they are tested at. You can by a 30 grade oil that is almost a 20, and you can buy a 30 that is almost a 40. And the SAE testing provides that an oil only has to test in that grade most of the time.

A lot of oil has been sold buy the manufacturers building an oil on the bottom of the grade. Then when testing, the oil is not worked hard enough, so it looks good on paper. But in service, the oil goes out of grade, pushrods start turning blue, pressure goes away and worse.


There is a whole load of science to lubrication, and we haven't even discussed dry film lubrication, which in certain cases is much more critical than fluid film lubrication.

I need a drink:banghead:
 
The W = winter thing is a misnomer. You can say it means winter if it helps you remember that its what the oil flows cold. Not just in winter. Before the W is what it flows cold. After the W is what it flows at operating temp. That simple.

Let's all remember. It's not necessarily cold when it's winter.

That's as much as I'll hijack this thread on oil and viscosity.

As for your oiling problem. It doesn't really sound like there is one. The heavier weight oil may be only slightly more pressure than a lower oil. If you're that worried about it. You could try running a 10W30. This is what I run and it's a good oil for our wild Alberta temperature swings. Bring it up to temp. See what your pushing then. You may be surprised. This will be the only way to see if there is a problem in my mind.
 
Lustle said:
The W = winter thing is a misnomer. Your ou can say it means winter if it helps you remember that its what the oil flows cold. Not just in winter. Before the W is what it flows cold. After the W is what it flows at operating temp. That simple.

Let's all remember. It's not necessarily cold when it's winter.

That's as much as I'll hijack this thread on oil and viscosity.

As for your oiling problem. It doesn't really sound like there is one. The heavier weight oil may be only slightly more pressure than a lower oil. If you're that worried about it. You could try running a 10W30. This is what I run and it's a good oil for our wild Alberta temperature swings. Bring it up to temp. See what your pushing then. You may be surprised. This will be the only way to see if there is a problem in my mind.
Click to expand...

Well it's a misnomer that the oil companies put in print. I agree that temperatures vary in winter months and in different locations. That's all semantics here. The point I was trying to make is how multiple viscosity oils are rated compared with single grade oil. The misconception is which oil and when they are thicker.
 
krazykuda said:
Viscosity does not INCREASE with temperature, it DECREASES (gets thinner and pours easier...)

Have you ever tried to change the oil when the engine is cold???

What about when it's hot???

Does the oil drain faster when it's cold or hot??? :scratch:
Click to expand...

I never said it did.
 
DartVadar said:
When I was priming the motor before installing it, the pushrods would be so flooded with oil they would have about a 1/4 of oil thickness going down along them. The springs were flooded with oil too. The oil would make the spring look solid if that makes sense. I mean everything is definitely getting oil up top! lol
Click to expand...
If you have the standard cam bearings which are not grooved, and no groove on the cam journals, you will have the 'timed' or interrupted' oil flow to the heads. If this is the case, and if you primed with the cam holes lined up so that one head was getting oil, then the observations above are pretty meaningless for actual engine operation, where the head is getting oil pressure only about 5% of the time.

And FWIW, your pressure numbers are good. With a heavier or lighter weight oil, the pressure where the relief valve opens is not going to vary much. So a heavier weight will not raise the peak pressure much as you seem to expect; it will just reach full pressure at a lower RPM with a heavier weight.

Keep in mind that a lighter weight will flow more volume and thus tend to cool internal parts better.
 
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