What's the deal with 7.5w grade oil?

[uart]

I notice that some Nissans here recommend 7.5w30 oil. Apparently the Nissan dealers sell it. I didn't even know that 7.5w "was a thing".

I know that 7.5w isn't a grade as defined under SAE J300, so how exactly are Nissan defining this. Is it just some kind of interpolation between the SAE 5W and SAE 10W cold performance specifications. Anyone know?

Thanks all.

 

[Olas]

Exactly halfway between the minimum 5w and the minimum 10w, so, as my copy of SAE J300 defines the Minimum KV of a 5w as 3.8 cSt, and gives a minimum KV of 4.1 cSt for a 10w, I'd guess at their 7.5w having a minimum Of 3.95 cSt.

Alternatively, you could dial the phone and ask them dirctly

 

[Shannow]

Originally Posted By: Olas
Exactly halfway between the minimum 5w and the minimum 10w, so, as my copy of SAE J300 defines the Minimum KV of a 5w as 3.8 cSt, and gives a minimum KV of 4.1 cSt for a 10w, I'd guess at their 7.5w having a minimum Of 3.95 cSt.


Can't be, as there's the pesky "30" that comes after it, so the KV100 has to be in the 30 range.

So it has to be some arbitrary Nissan choice of cold cranking behaviours between 5W and 10W...which makes it a 10W30 if it can't be labelled as a 5W30.

Gimmick, which makes them sound like they are tailoring something special for their engines...It's pretty common by the looks of things.

 

[Olas]

Table 3 – SAE Viscosity Grades - Engines

SAE Viscosity Grades for Engine Oils (SAE J300) - December 1999

Grade

Absolute Viscosity (cP)

Kinematic Viscosity (cSt)

HTHS (cP) 150°C

Maximum Cold Cranking

Maximum Cold Pumping

Minimum

Maximum

High-Temperature- High-Shear

0W

6 200 @ -35°C

60 000 @ -40°C

3.8

-

-

5W

6 600 @ -30°C

60 000 @ -35°C

3.8

-

-

10W

7 000 @ -25°C

60 000 @ -30°C

4.1

-

-

15W

7 000 @ -20°C

60 000 @ -25°C

5.6

-

-

20W

9 500 @ -15°C

60 000 @ -20°C

5.6

-

-

25W

13 000 @ -10°C

60 000 @ -15°C

9.3

-

-

20

-

-

5.6


2.6

30

-

-

9.3


2.9

40

-

-

12.5


2.9 (1)

40

-

-

12.5


3.7 (2)

50

-

-

16.3


3.7

60

-

-

21.9


3.7

 

[Olas]

That didn't format very well...

Look here http://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm

 

[Shannow]

Here's one.

 

[Colt45ws]

Maybe its hitting 7000mpa@-30C?
I really have no idea why they would do this. Its really splitting hairs. There are plenty of oils that can meet 5w30. And really the climate there is such that you would never have any problem with a 10W30, either.
I agree with Shannow; they are trying to make the uninformed think the oil is special.
Where is this written at? Oil cap? Owners manual?

 

[uart]

Originally Posted By: Shannow

Can't be, as there's the pesky "30" that comes after it, so the KV100 has to be in the 30 range


Yes definitely Shannow. It can't be an interpolation on of the 5w and 10w 100C specs, as they're irrelevant in a xw30. It has to be some kind of interpolation on the cold viscosity / cold cranking specs.

I guess it's either gonna be something like 6800 mPa-s max at -27.5C, or else 61000 (or 62000) mPa-s max at -32.5C. Or maybe both of the above.

Originally Posted By: Shannow
Gimmick, which makes them sound like they are tailoring something special for their engines...It's pretty common by the looks of things.

Yeah that's what I think too. Plus when people go to change their oil they're going to find that parts places (like supercheap etc) don't carry 7.5w30 (not surprisingly as it doesn't really exist), so are going to think they need to do to the dealer. Nice marketing trick.

 

[NHGUY]

Who could trust a car company whose logo is a hamburger?

 

[dlundblad]

Just thinking out loud.

I wonder if 3 quarts of 10w30 and 3 quarts of 5w30 (same brand/ type) would make a nice shear stable winter oil??

 

[demarpaint]

Originally Posted By: uart
Originally Posted By: Shannow

Can't be, as there's the pesky "30" that comes after it, so the KV100 has to be in the 30 range


Yes definitely Shannow. It can't be an interpolation on of the 5w and 10w 100C specs, as they're irrelevant in a xw30. It has to be some kind of interpolation on the cold viscosity / cold cranking specs.

I guess it's either gonna be something like 6800 mPa-s max at -27.5C, or else 61000 (or 62000) mPa-s max at -32.5C. Or maybe both of the above.

Originally Posted By: Shannow
Gimmick, which makes them sound like they are tailoring something special for their engines...It's pretty common by the looks of things.

Yeah that's what I think too. Plus when people go to change their oil they're going to find that parts places (like supercheap etc) don't carry 7.5w30 (not surprisingly as it doesn't really exist), so are going to think they need to do to the dealer. Nice marketing trick.


I agree.

 

[Vern_in_IL]

Originally Posted By: NHGUY
Who could trust a car company whose logo is a hamburger?


It's not a hamburger, it's the rising sun of Japan!

 

[spasm3]

Originally Posted By: demarpaint
Originally Posted By: uart
Originally Posted By: Shannow

Can't be, as there's the pesky "30" that comes after it, so the KV100 has to be in the 30 range


Yes definitely Shannow. It can't be an interpolation on of the 5w and 10w 100C specs, as they're irrelevant in a xw30. It has to be some kind of interpolation on the cold viscosity / cold cranking specs.

I guess it's either gonna be something like 6800 mPa-s max at -27.5C, or else 61000 (or 62000) mPa-s max at -32.5C. Or maybe both of the above.

Originally Posted By: Shannow
Gimmick, which makes them sound like they are tailoring something special for their engines...It's pretty common by the looks of things.

Yeah that's what I think too. Plus when people go to change their oil they're going to find that parts places (like supercheap etc) don't carry 7.5w30 (not surprisingly as it doesn't really exist), so are going to think they need to do to the dealer. Nice marketing trick.


I agree.


I agree as well, I would not be surprised to see another company get the idea, and specify a 2.5w 20.

 

[Chuckinator]

Polaris specs 2w-50 for my sportsman 500

 

[Shannow]

Like I said, it's a gimmick

that makes the end user think that there is something unique in the OEM's oil...that will have been brewed and bottled by the lowest bidder

 

[A_Harman]

Originally Posted By: Shannow

Here's one.


I've never seen a copy of the J300 spec where the MRV's increase from 60,000. I thought 60,000 was the max allowable at all the test temperatures. Is that a mistake on the chart?