Why would you ever want to run 10W-30 over 5W-30?

[Stopsign32v]

volatility could lead to intake tract deposits, but to be fair I consider it more of an indication of the base oils used and what those could or couldn't do.

viscosity modifiers are added to make oil less thin than they would be when hot. Strip the viscosity modifier from a 5W-40 and you likely end up with a 0W-20.

J

Thread 'Castrol 5W-40, QS 5W-40, QS UD 10W-30, Amsoil SS 10W-30 Volatility Results - Dec. 2024'

Dec 18, 2024

Castrol 5W-40 (C 5W-40), Quaker State 5W-40 API SP (QS 5W-40), Quaker State Ultimate Durability 10W-30 (QS UD 10W-30), Amsoil SS 10W-30 (Ams SS 10W-30).

Please see the following two threads about past results.
https://bobistheoilguy.com/forums/t...rotection-volatility-results-nov-2024.389905/

The test procedure was like the previous except the oil temperature was ~420 F throughout entire test. Also different is...

• JAG
• Replies: 1
• Forum: Passenger Car Motor Oil (PCMO) - Gasoline Vehicles

• 

No oil can get into my intake tract, I run a catch can. Intake tract is closed off to only air.

So from what you are saying, it seems 5W-40 would be best for me over the 10W-30?

 

[Analog-1]

10W-30 has a higher base oil viscosity mix, which timing chains love.

So all the engines that have 100's of thousands of miles on them using 0w20-5w20 have bad timing chains ? At this point it's safe to say the lower weight oils work period. My Civic has 237.000 miles the chain is a no issue.

 

[Kestas]

For the same viscosity, there is a 15°F difference between the two grades.
The viscosity of 10W-30 at 45° is the same as the viscosity of 5W-30 at 30°F.

 

[OVERKILL]

volatility could lead to intake tract deposits, but to be fair I consider it more of an indication of the base oils used and what those could or couldn't do.

viscosity modifiers are added to make oil less thin than they would be when hot. Strip the viscosity modifier from a 5W-40 and you likely end up with a 0W-20.

J

Thread 'Castrol 5W-40, QS 5W-40, QS UD 10W-30, Amsoil SS 10W-30 Volatility Results - Dec. 2024'

Dec 18, 2024

Castrol 5W-40 (C 5W-40), Quaker State 5W-40 API SP (QS 5W-40), Quaker State Ultimate Durability 10W-30 (QS UD 10W-30), Amsoil SS 10W-30 (Ams SS 10W-30).

Please see the following two threads about past results.
https://bobistheoilguy.com/forums/t...rotection-volatility-results-nov-2024.389905/

The test procedure was like the previous except the oil temperature was ~420 F throughout entire test. Also different is...

• JAG
• Replies: 1
• Forum: Passenger Car Motor Oil (PCMO) - Gasoline Vehicles

• 

And the 10W-30 could be 85% 5cSt Group II:

While the 5W-40 could be 45% 6cSt PAO and 25% 8cSt PAO:

There are SO many ways to skin the cat here.

 

[Stopsign32v]

So all the engines that have 100's of thousands of miles on them using 0w20-5w20 have bad timing chains ? At this point it's safe to say the lower weight oils work period. My Civic has 237.000 miles the chain is a no issue.

For the same viscosity, there is a 15°F difference between the two grades.
The viscosity of 10W-30 at 45° is the same as the viscosity of 5W-30 at 30°F.

Are you guys able to put this into layman's term? From what I'm gathering we are trying to align with the 5W oils are as good/better than the 10W???

 

[kschachn]

higher MOFT will help even then, if the oil film thickness exceeds the debris size, no wear.

No, there is always wear.

 

[SC Maintenance]

What about 5W-40 instead of 5W-30? I run Rotella T6 and they have 10W-30 and 5W-40.

I have run all three of these in my Nissan VQ 40's. No issues.

Unless your running really long OCI or whatever, or unless it gets very cold where you are, I have no idea why it would matter whether it was 0W, 5W, 10W, or 15W honestly. Having said that, I think the "best" formulations of base stock are in the 0W-30 and 0W-40 if I properly understand what the smart people here say.

not sure why they don't have 10W-40

Still exists, but was way more common decades ago. I used to run it in the summer in my old Ford 300-6's. There however is really no reason - just go 15W-40

 

[kschachn]

Are you guys able to put this into layman's term? From what I'm gathering we are trying to align with the 5W oils are as good/better than the 10W???

The “goodness” is relatively unrelated to the winter rating. Goodness is represented by the licenses, specifications or approvals the oil holds (or does not hold). There are exceptions but if you pick an oil with an approval such as VW 504 00, Porsche A40 or Mercedes-Benz 229.5 you’ll be miles ahead in protecting that engine.

 

[Stopsign32v]

if you pick an oil with an approval such as VW 504 00, Porsche A40 or Mercedes-Benz 229.5 you’ll be miles ahead in protecting that engine.

Why? And what oils might this be?

 

[kschachn]

Why? And what oils might this be?

The ones with the approval. They have demonstrated wear protection, sufficient HT/HS, and proven oxidation and deposit control.

Relatively inexpensive and available at Walmart.

 

[Lyman]

The climate where I live is typically between 41* and 87*. During the summer months, it is in the 90s and up into the 100s. I have been running 10w30 most of my life. It's a popular choice here.

 

[350Rocket]

Why? And what oils might this be?

For example 0w40 FS from M1 or the Castrol euro variant.
Basically what he's saying is the requirements of the application dictate how "good" the oil is, much more so than the viscosity. So looking for those approvals will give you a better oil.

It might not make a difference if you're not going for 500k miles or racing or something, but if you're looking for one of the best options then the approvals are one way to find it.

 

[Chris142]

That’s an appropriate winter rating below 0F. I wouldn’t use one with a 10W below 0F.

Why not use 5w 30 above 0f?

My bad 0c...
Here's what my book says. Why can't I use 5w30 above 32f?

 

[burbguy82]

I have wondered this, but in reverse..........if the temps are proper, why run 5w30.......

Notice the flash and fire point and NOACK numbers are "Superior" in the 10w30

pour point is the same

5w30 is a smidge thicker than 10w30 at operation temp

HTHS is "better" in the 10w vs the 5w.

it seems there is a trend, using Amsoil site for ease, that 10w30 is always way lower NOACK, higher HTHS, higher fire and flash point.......and less viscous at operating temp.

Amsoil SS is the same trend.

 

[kschachn]

Why not use 5w 30 above 0f?

My bad 0c...
Here's what my book says. Why can't I use 5w30 above 32f?

View attachment 255642

Sometimes those charts defy reason.

 

[OVERKILL]

it seems there is a trend, using Amsoil site for ease, that 10w30 is always way lower NOACK, higher HTHS, higher fire and flash point.......and less viscous at operating temp.

That may be the trend for certain brands of oils with a "no holds barred" formulation approach, but if we are talking your Walmart shelf offering, as the blending guide examples I provided earlier show, you can't just make that assumption. A 10W-30 isn't eligible for dexos or many other OE specs so there's no real incentive to make it "better" than a 5W-30 that is dexos and carries approvals.

This Havoline conventional 10W-30 for example, certainly isn't anything to write home about:

Heck, neither was this Royal Purple 10W-30:

And of course then we have 5W-30's with no VII in them, like those found in HPL's No VII series.

 

[wlk]

I liked 10w30 in my older GM 3.1l and 5.7l that had piston slap as it was quieter while warming up. 10w30 is what my F350 spec's. I will probably start using Starfire hd 10w30 for my current fleet once/if I ever get through my sales oil stash.

 

[Jetronic]

No, there is always wear.

And the 10W-30 could be 85% 5cSt Group II: View attachment 255613

While the 5W-40 could be 45% 6cSt PAO and 25% 8cSt PAO:
View attachment 255614

There are SO many ways to skin the cat here.

could be, but the 10w-30 I'm buying isn't grII, and the off the shelf 5w-40 isn't going to be 60% PAO. I did preface synthetic 10W-30 to specifically exclude this comment.

 

[SR5]

A good comparison is looking at LiquiMoly Molygen oils, a good quality German made Group-III synthetic, that has decent data on their product information PDF. Both are API SP and ILSAC GF-6A.

The 5W30 has a KV100 of 10.8 cSt, Noack volatility of 9.8%, a pour point -42C and a flash point of 224C.
The 10W30 has a KV100 of 11.0 cSt, Noack volatility of 8.2%, a pour point-42C and a flash point of 238C.

This shows a number of things, firstly pour points don't reflect cold weather starting performance. This is better measured by the cold cranking and cold pump tests conducted to establish their correct Winter (W) performance. A 10Wx oil is good down to around 0F / -20C.

Also, a well formulated 10W30 should be a point or two less volatile than a similarly formulated 5W30. In an apples with apples comparison.

Ref:
https://pim.liqui-moly.de/pdf/en_GB/liqui/35/P003599

https://pim.liqui-moly.de/pdf/en_GB/liqui/76/P001757

 

[burbguy82]

That may be the trend for certain brands of oils with a "no holds barred" formulation approach, but if we are talking your Walmart shelf offering, as the blending guide examples I provided earlier show, you can't just make that assumption. A 10W-30 isn't eligible for dexos or many other OE specs so there's no real incentive to make it "better" than a 5W-30 that is dexos and carries approvals.

This Havoline conventional 10W-30 for example, certainly isn't anything to write home about:
View attachment 255653

Heck, neither was this Royal Purple 10W-30:
View attachment 255654

And of course then we have 5W-30's with no VII in them, like those found in HPL's No VII series.

So 10w30....... all other things being equal will not exhibit "more durable" characteristics like noted before?

Can you compare yours to a like 5w30?


As I have shown endlessly, my ignorance to some of these values regarding oil specs, I am trying to learn the magic....but to me, a higher flash point and higher volatility number especially in significant percentages has to mean something.........something meaningful so to speak.