Oil experts, please help me educate this guy...

[TurboTravis]

http://www.shift518.com/showthread.php?t=28823 Read that thread starting at post 3. I'm "TurboTravis", he's "Volvchandr" He thinks that oil ratings make no sense because a multigrade oil is thicker when it's cold, and since it's thicker when cold, it should have a higher viscosity number, not lower. He's failing to take into consideration that the "W" rating is tested at low temps and the non "W" number is tested at higher temps. Feel free to sign up and post, I encourage you to!

 

[Bluestream]

Good Luck!

 

[chevrofreak]

That guy is beyond help. He is stuck on his misconception that oil viscosity ratings are determined at 32F and "operating temperature" and that they are measured using the same methodology. He needs to read and understand SAE J300.

 

[cchase]

I don't have much faith in the maturity of that forum based on everyones behavior in the thread. You've posted some incorrect information although the admin has stuff even more confused.

 

[FowVay]

TurboTravis, you're not exactly correct in your understanding either. The cold flow properties are not determined at 32ºF. They're actually determined at different temperatures depending on the desired rating. A quick perusal of the SAE J300 chart will show simply that: 0W oils are measured at -35ºC (not 32ºF). They need a viscosity of no more than 6200 cP's at this temp. 5W oils are measured at -30ºC (not 32ºF). They need a viscosity of no more than 6500 cP's at this temp. 10W oils are measured at -25ºC (not 32ºF). They need a viscosity of no more than 7000 cP's at this temp. These measurements go on through the entire viscosity spread. Ask the other forum member if he actually knows the viscosity of a 5W-30 oil at 212ºF (100ºC). The viscosity will be between 9.3 cSt's and 12.5 cSt's. Also ask him if he knows the viscosity of the same oil at freezing (32ºF). The number will be upwards of 300 cSt's. Ask him how 300 cSt's is thinner than 10 cSt's. There is quite a bit of misinformation on this subject.

 

[TurboTravis]

Originally Posted By: FowVay

TurboTravis, you're not exactly correct in your understanding either. The cold flow properties are not determined at 32ºF. They're actually determined at different temperatures depending on the desired rating. A quick perusal of the SAE J300 chart will show simply that: 0W oils are measured at -35ºC (not 32ºF). They need a viscosity of no more than 6200 cP's at this temp. 5W oils are measured at -30ºC (not 32ºF). They need a viscosity of no more than 6500 cP's at this temp. 10W oils are measured at -25ºC (not 32ºF). They need a viscosity of no more than 7000 cP's at this temp. These measurements go on through the entire viscosity spread. Ask the other forum member if he actually knows the viscosity of a 5W-30 oil at 212ºF (100ºC). The viscosity will be between 9.3 cSt's and 12.5 cSt's. Also ask him if he knows the viscosity of the same oil at freezing (32ºF). The number will be upwards of 300 cSt's. Ask him how 300 cSt's is thinner than 10 cSt's. There is quite a bit of misinformation on this subject.

I realize and understand your post-I was just trying to keep things as simple as possible by generalizing some facts. The information you posted is in chart(s) that I linked to/posted.

 

[teddyboy]

My admitedly ill informed understanding of this is the following. At cold temperature a 5W30 oil flows like an oil whose viscosity falls in the 5 range and at operating temperature it flows like an oil whose viscosity is in the 30 range. However, an oil whose viscoisty is in the 30 range is thinner at operating temperature than an oil whose viscosity is in the 5 range is at a cold (say 32F) temperature. That's why the oil is thicker when it is cold and thinner when hot. Is my understanding correct?

 

[A_Harman]

Your understanding is incorrect. Before the advent of multi-vis oils in the early 50's, there were W-rated oils, and there were regular oils in viscosity grades that were defined in SAE J300. Back in those days, you put a W-grade oil in your crankcase for cold weather, and regular grade oils for warm weather. What you actually have with a 10W-30 oil is one that meets the low temperature viscosity requirements of a 10W oil, and the high temperature viscosity of a 30 grade oil.

 

[TurboTravis]

It's getting worse...he STILL thinks that multigrade oil ratings do not make sense. Help!

 

[chevrofreak]

Give up. Tell him that the people at BITOG think he's an idiot, and leave it at that.

 

[aquariuscsm]

So,say a 5W50 oil for example. Does it have less *real* oil per se,and more viscosity improvers? Would a mono grade 50 oil have more *real* oil in it vs a 5W50? Am I understanding mono vs multi grades correctly?

 

[A_Harman]

Yes, a straight 50-weight will not have any viscosity improvers, and its viscosity index will be less than 120. Its shear stability will be dependent entirely on the quality of the base stock. A 5w50 will have VII's in it, but since not all base stocks have the same viscosity index, some 5w50's will have less VII's than others.

 

[chevrofreak]

Originally Posted By: aquariuscsm

So,say a 5W50 oil for example. Does it have less *real* oil per se,and more viscosity improvers? Would a mono grade 50 oil have more *real* oil in it vs a 5W50? Am I understanding mono vs multi grades correctly?

Monograde oils are not allowed to have VII's or a VI higher than the low 100 range or it has to be marketed as a multi-grade.

 

[mechtech2]

Originally Posted By: teddyboy

My admitedly ill informed understanding of this is the following. At cold temperature a 5W30 oil flows like an oil whose viscosity falls in the 5 range and at operating temperature it flows like an oil whose viscosity is in the 30 range. However, an oil whose viscoisty is in the 30 range is thinner at operating temperature than an oil whose viscosity is in the 5 range is at a cold (say 32F) temperature. That's why the oil is thicker when it is cold and thinner when hot. Is my understanding correct?

Seems right on the money. What flaw is there to this thinking? This is what happens.

 

[GMorg]

You can't save the world.