When is a 5W-30 at 5w and then a 30W oil?

[chevrofreak]

Originally Posted By: Steve S
Originally Posted By: milwaukee
Steve,

A 5w-30 is like syrup when cold and water when hot/operating temp? Syrup does NOT "thicken" to water. The syrup turns into water i.e. it becomes thinner. What is so difficult? The numbers 5w and 30 are values NOT thickness ratings.
Hot 30 wt is thicker than hot 5wt what is the problem with understanding that? at any temperature 30 is thicker than 5. 5w-30 oil has to thicken to equal a 30 wt when hot otherwise it will be a 5w. I am not debating that heat thins out a straight wt oil I knew that 45 years ago.


At no point does a multigrade oil increase in viscosity due to increased heat. Period. It simply does not thin as much, because the VII's expand and make it have more viscosity than it otherwise would.

 

[Samilcar]

Originally Posted By: d00df00d
Originally Posted By: Steve S
Hot 30 wt is thicker than hot 5wt what is the problem with understanding that?

The problem is that 5-weight oil has no relevance to this discussion.


Correct.

 

[Drew99GT]

Originally Posted By: bullwinkle
5W30 BEHAVES like a 5W at cold temperatures, then BEHAVES (viscosity-wise) like a 30W at operating temperatures-at least until the VIs shear/wear out.


Cripes fellas, this has been discussed ad-nauseum here! This is the basics! We are all oil nerds, some of with 14,000 posts on this site, and we can't even get this right???

Here is how ANY multi-viscosity oil "behaves":

At each temperature designated for cold weather performance as outlined by the SAE oil grading system, an oil of each grade will pass the corresponding SAE cold cranking and cold pumping test at it's given temperature. In the case of 5w, the SAE test are conducted at -30C for cold pumping and -25C for cold cranking. An oil labeled 5w must be no more then 6,600 centipoise at -25C in a cold cranking simulator, and no more then 60,000 centipoise in a mini rotary viscometer.

Now, on to the operating temperature viscosity, the 2nd number in a multi viscosity oil. This number has NO RELATION to the other number preceding the W. NON. Zip zilch notta. There's no "it behaves like a 5 weight when cold and doesn't thin more then a 30 weight" stuff. The 2nd number is the kinematic actual measured viscosity of the oil at operating temperature, which is a ton thinner then the oil will be when it's cold. In the case of a 30 weight oil, as in say, 5w-30, or 10w-30, the 2nd number would fall between 9.3 and 12.49 centistokes.

 

[Gary Allan]

Drew: What's missing is the "in between" stuff. With stating it only that way people think that a 5w-50 gets a free ride to 100C and is no different than a 5w-20 up to 100C (or some morphed adapted variation of that theme).

Assuming the same VI and 100C visc, there is no difference between a 5w/10w/20w fluid @ 40C ..30C ..20C ..etc...etc. Heavier and thicker is always heavier and thicker even if it reacts within limits of the designated "W" spec.

 

[Mustang Man]

All the #w means is how quickly and easily an oil will flow when cold. The lower the number the better. This is EXACTLY why I am running 0w-30 YEAR ROUND instead of 5w-30 or 10w-30.

When at operating temperature they all have about the same viscosity. Mobil 1 for example...

0w-30
cSt @ 40ºC 63.1
cSt @ 100ºC 11.0

5w-30
cSt @ 40ºC 64.8
cSt @ 100ºC 11.3

Remember, 40ºC = 104ºF. I would bet those numbers would be even more different at 70ºF and more so at 50ºF and at 20ºF and so on with the advantage being in 0w's favor.

 

[BobFout]

Originally Posted By: Mustang Man
All the #w means is how quickly and easily an oil will flow when cold. The lower the number the better. This is EXACTLY why I am running 0w-30 YEAR ROUND instead of 5w-30 or 10w-30.

When at operating temperature they all have about the same viscosity. Mobil 1 for example...

0w-30
cSt @ 40ºC 63.1
cSt @ 100ºC 11.0

5w-30
cSt @ 40ºC 64.8
cSt @ 100ºC 11.3

Remember, 40ºC = 104ºF. I would bet those numbers would be even more different at 70ºF and more so at 50ºF and at 20ºF and so on with the advantage being in 0w's favor.


0w30 @ 20C = 132 cSt
5w30 @ 20C = 136 cSt

0w30 @ 0C = 310 cSt
5w30 @ 0C = 318 cSt

For those two oils, the visco at 40C and 100C are so close, they will have very similar flow on down to the temp at which the 5w and 0w distinction is made. Even then the difference could be minor, enough for one to just eek into 5w and the other into 0w.

 

[Mustang Man]

Interesting. One would think the numbers would be more different as the temperature decreased.

 

[mechanicx]

Originally Posted By: BobFout
Originally Posted By: Mustang Man
All the #w means is how quickly and easily an oil will flow when cold. The lower the number the better. This is EXACTLY why I am running 0w-30 YEAR ROUND instead of 5w-30 or 10w-30.

When at operating temperature they all have about the same viscosity. Mobil 1 for example...

0w-30
cSt @ 40ºC 63.1
cSt @ 100ºC 11.0

5w-30
cSt @ 40ºC 64.8
cSt @ 100ºC 11.3

Remember, 40ºC = 104ºF. I would bet those numbers would be even more different at 70ºF and more so at 50ºF and at 20ºF and so on with the advantage being in 0w's favor.


0w30 @ 20C = 132 cSt
5w30 @ 20C = 136 cSt

0w30 @ 0C = 310 cSt
5w30 @ 0C = 318 cSt

For those two oils, the visco at 40C and 100C are so close, they will have very similar flow on down to the temp at which the 5w and 0w distinction is made. Even then the difference could be minor, enough for one to just eek into 5w and the other into 0w.


This is why I prefer a 5-xx or 10-xx in Summer. It can have lower volatility and less VII. And really even in Winter around here a 5W and even 10W gets by decently. Of course if you are comparing a 0W-30 to a 5W30 dino the synthetic probably comes out ahead but not on price. But compare a 5W- or 10W- synthetic in the Summer or for those in the south and 0W is not ahead.

 

[Boss302fan]

OK... Which is better year round in the Midwest? Air temps around -30 in the winter(usually 10 degrees average) and summer temps around 90 degrees.

A 0-30 syn, 5W-30 syn or a 10W-30 syn? I have always thought that any 10W30 oil is a better weight oil. The 5 and 10 usually pour about the same in cold weather so would'nt the 10W30 syn be the better all around oil?

 

[mechanicx]

Well I think if you are talking year around and you get that cold regularly in Wisconsin then you would probably be ahead with a 0W30 or 5W30. Here in Winter it is usually in the teens and although it usually drops to near 0 or a little below a few days each Winter and the record is -23, the average is probably closer to 20 and not likely to go below 0.

The thing is I don't run oil for more than 6 months and do a lot of short trips. So I'd run 0W30 Winter and then 5W or 10W30 Summer. If I were to run one oil year around it would be 5W30.

 

[Jim Allen]

Originally Posted By: Boss302fan
OK... Which is better year round in the Midwest? Air temps around -30 in the winter(usually 10 degrees average) and summer temps around 90 degrees.

A 0-30 syn, 5W-30 syn or a 10W-30 syn? I have always thought that any 10W30 oil is a better weight oil. The 5 and 10 usually pour about the same in cold weather so would'nt the 10W30 syn be the better all around oil?


Awful lot of variables in that.

For one thing, a 30 is a 30 once the engine is warmed up. The potential for shearing over time is higher in the 0W, 5W but the syns are pretty good at resisting that. Maybe we are too fixated on pour points here. The point between startup and warmed up is important too and for, that reason, I'd go with a 0W or a 5W unless there is good reason not to. That warmup phase is important even outside of winter.

I'd say it depends on how many cold starts the engine will endure and the warmup cycle. If it gets short hopped, you definitely want the lighter oils because the engine is always in the warmup phase. If the engine starts once and gets good runs to bring the oil up to temp and stays there, then the heavier grade is fine. To my mind, the only time you really "need" a more robust 10W or 15W is in extreme duty situations an/ or with an engine that's a known shear-monster. Or a dilution-monster. I guess the only reall downfall to the 10W would be a loss of FE... but that would likely be most apparent for short hoppers.

 

[Mustang Man]

My Mustang starts up just fine using 0w-30 in the +90ºF weather we have been having in Illinois. I have absolutely no funny engine noises on start up. The oil pressure shoots right up. This is the good thing about 0w. My car is at operating temperature in about 7-10 minutes making the 0w meaningless as I am at the same weight as 5w-30 and 10w-30 at that point.

My biggest concern is start up which is when most engine wear occurs. So running the thinnest oil possible at that point is preferred.

Don't hold me to this, but I am pretty sure 0w-30 only comes in synthetic. I haven't seen any 0w-30 dino at the places I shop for car stuff. Synthetics resist shear better than dino because synthetic #w-30 all are made as 30 whereas 5w-30 is a 5w oil with VII to make it a 30 when hot.

As Dr. Haas states...

http://www.bobistheoilguy.com/cms/index.php?option=com_content&view=article&id=81

"A 10W-30 multi-grade mineral based oil is made from a 10 grade oil and has VI improvers added to thicken the product in a 212 F engine."

"A 10W-30 synthetic oil is based on a 30 grade oil."

 

[Boss302fan]

I guess then summer months use 10W30 syn and winter months go with 0W30 syn...

 

[Gary Allan]

Quote:
My biggest concern is start up which is when most engine wear occurs. So running the thinnest oil possible at that point is preferred.


But one must understand that start up wear is a curve from initial start to full warm up. It's just about all of the unavoidable cylinder:ring wear that occurs. That's how SAE defines it. That's NOT how Castrol wants you to understand it.

My ponderings on the topic find 3 main origins for the wear. None of them have anything to do with viscosity, per se.

(in no order of hierarchy in the ongoing learning process)

Ill fitment of parts. Pistons aren't fully expanded, etc..etc.

Additive activation.

Corrosive aspects of combustion byproducts and moisture on the cold cylinder walls. - Apparently there's some lingering etching issue involved that doesn't recede until moisture droplets can't form on the cylinder walls. You're producing about 1.4 gallons of water for every gallon of fuel you burn.

Some attribute the fuel/moisture corrosive component as being the lion's share of this unavoidable wear curve. I've yet to see sufficient evidence to convince me of this.


Now...sure..you use a SAE 50 @ -10F ..and the engine coughs and stumbles and takes 45 seconds to show pressure ...but..

 

[mechanicx]

Originally Posted By: Mustang Man

Don't hold me to this, but I am pretty sure 0w-30 only comes in synthetic. I haven't seen any 0w-30 dino at the places I shop for car stuff. Synthetics resist shear better than dino because synthetic #w-30 all are made as 30 whereas 5w-30 is a 5w oil with VII to make it a 30 when hot.

As Dr. Haas states...

http://www.bobistheoilguy.com/cms/index.php?option=com_content&view=article&id=81

"A 10W-30 multi-grade mineral based oil is made from a 10 grade oil and has VI improvers added to thicken the product in a 212 F engine."

"A 10W-30 synthetic oil is based on a 30 grade oil."


I think that is only true with Group IV and V synthetics 10W30 and maybe 5W30. For most group III 0W30, they would have to use VII and a lighter oil than an equivalent 5W30 or 10W30. So the latter usually has the volatility, sheer and HTHS advantage. But yeah any 0W30 probably beats a 5W30 on all counts except price but not by that much.

As far as more engine wear on warm up, I'm not sure if a 0W prevents the wear all that much. Above ~70 degrees or so a 0W isn't all that much thinner than most 5W and even 10W's anyway.

 

[Gary Allan]

Taking a 10 weight oil and adding VII to mimic 30 weight at 100C is one way to make the multivisc fluid. It won't last long. Add PPD (pour point depressants) and you don't need as thin a base stock, so you can get a 20 grade base stock to meet the cold specs ..and use less VII to achieve your hot visc requirement.

Then you magically come up with Group II/II+ base stocks that are clear and aren't going to wax and gel and become unpumpable at colder temps..and you get even more latitude in how you configure your blend. Even before that you have some magic oil catalyst pulled out of some engineers behind and find that you can do even more amazing stuff.

 

[SpitfireS]

The ratio between the viscosity of a 0W/5W-30 at a cold (10C) start and the same oil at operating temp is 1:~25.
IMhO that would mean the oil pump "must" be (partly) in relief during a cold start pumping the thick oil around?
Yes? No? Maybe?
IMhO that would mean more thiner-when-cold-oil is pushed through a cold engine, slightly reducing/shortening the time-to-temp curve.
A little more oil is IMO better that thicker oil staying at a hot surface a little longer.
I can't explain it, just a feeling

As long as it shortens the wear curve at the beginning, where the curve is steep, one would get the most gain, as in: less start-up wear.
I hope

 

[Gary Allan]

Quote:
Yes? No? Maybe?


Who knows?

Quote:
IMhO that would mean more thiner-when-cold-oil is pushed through a cold engine



This assumes that just because it has a 0w on the front end of it that it is indeed a "thinner" fluid at a given temp than a 5w.

I don't know how many times and how many more examples I can cite here.

Here's a 0w

Typical Properties

Mobil 1 0W-40
Value
Viscosity, ASTM D 445
cSt @ 40º C 78.3
cSt @ 100º C 14
Sulfated Ash, wt%, ASTM D 874 1.2
Phosphorous 0.1
Flash Point, ºC, ASTM D 92 230
Density @15º C kg/l, ASTM D 4052 0.85
Total Base Number (TBN) 11.3
MRV at -40ºC 26242
Viscosity Index 186
HTHS Viscosity, mPa•s @ 150ºC, ASTM D 4683 3.7

Here's a 5w

Typical Properties

Mobil 1 5W-30
SAE Grade 5W-30
Viscosity, ASTM D 445
cSt @ 40º C 64.8
cSt @ 100º C 11.3
Viscosity Index, ASTM D 2270 169
Sulfated Ash, wt%, ASTM D 874 1.0
HTHS Viscosity, mPa·s @ 150ºC ASTM D 4683 3.09
Pour Point, ºC, ASTM D 5949 -48
Flash Point, ºC, ASTM D 92 230
Density @15º C kg/l, ASTM D 4052 0.80


How in the world can a 0w be heavier @ 40C?? It's a 0w, right? How about 30C? Still heavier ..what's wrong with the world!!!! It's a 0w and is supposed to be easier to pump every day ..all the time!!

A heavier fluid is always a heavier fluid.

 

[mechanicx]

What you see here is that 0W is basically meaningless except at very cold temperatures and maybe at colder than at least Summer "cold start" temps. You see that the 0W40 has a higher visocity index which is probably due to more VII, and you would also expect due to the higher VI the 0W40 to be thinner than the 5W30 at some point maybe around 0F but who knows. I'm not sure but I think VII start to decrease the thinning of oil at around room temperatures. It would be nice to have had the volatility of these 2 oils.

 

[SpitfireS]

Well.... I was talking about 0W-30 and 5W-30.
I could have been more clear about that.
The 2 types of 0W-30's I have used (Shell Helix Ultra X and SSO) are both thinner at 10C than the thinnest 5W-30 in my list (being Amsoil XLF)
221 & 236 respectively vs 245 cSt @ 10C.
Calculated (okay.. it could be this is all too cold to be done correctly) with the "CapeCanaveral" website that is no longer online - a I just noticed.
Anyway, I used Visc @ 100C and 40C and VI, all numbers by manufacturer's spec.

It just ain't fair to drag 40 weights into this.