Why would M1 5w30 be thinner than 0w-40?

[License2ILL]

Mobil 1 0W-40 Value
Viscosity, cSt (ASTM D445)
@ 40º C 75
@ 100º C 13.5
Viscosity Index 185
MRV at -40ºC, cP (ASTM D4684) 31,000
HTHS Viscosity, mPa•s @ 150ºC, (ASTM D4683) 3.8
Total Base Number (ASTM D2896) 11.8
Sulfated Ash, wt% (ASTM D874) 1.3
Phosphorous, wt% (ASTM D4981) 0.1
Flash Point, ºC (ASTM D92) 230
Density @15.6 ºC, g/ml (ASTM D4052) 0.85
----------------------------------------------------
Mobil 1 5W-30
SAE Grade 5W-30
Viscosity @ 100ºC, cSt (ASTM D445) 11.0
Viscosity, @ 40ºC, cSt (ASTM D445) 61.7
Viscosity Index 172
Sulfated Ash, wt% (ASTM D874) 0.8
HTHS Viscosity, mPa•s @ 150ºC (ASTM D4683) 3.1
Pour Point, ºC (ASTM D97) -42
Flash Point, ºC (ASTM D92) 230
Density @15.6 ºC, mg/l (ASTM D4052) 0.855
------------------------------------------------------
Mobil 1 10W-30
SAE Grade 10W-30
Viscosity @ 100ºC, cSt (ASTM D445) 10.1
Viscosity, @ 40ºC, cSt (ASTM D445) 63.2
Viscosity Index 146
Sulfated Ash, wt% (ASTM D874) 0.8
HTHS Viscosity, mPa•s @ 150ºC (ASTM D4683) 3.0
Pour Point, ºC (ASTM D97) -42
Flash Point, ºC (ASTM D92) 232
Density @15.6 ºC, g/ml (ASTM D 4052) 0.859

M1 0w-40 actually seems thicker at 40c than 5w-30.

"Weigh"ing both is a little difficult becuase 0w also has a great HTHS. The thinner 5w should offer a little more startup protection but the benefits of the 0w-40 package make it difficult to disregard. It also brands the long life usage from BMW. But it does not carry any GM approval.

Why does GM approve so much more the 5w-30? it would seem like the 0w-40 formula offers more protection and also has more zddp.

I dont think i can mix the 2 becuz the oil pan pick up on a chevy small block is so low in the pan..it would only pickup the heavier of the two at startup so if i wanted to stay with Mobil 1 I would have to choose 1 or the other.

 

[Steve S]

How will 5w offer a little more startup protection?
G.M. uses 5w-30 due to CAFE . Directly from a G.M enginner during one of my continuing education auto tech clases
Why would the oil pickup being so low in the pan only pickup the heavier of the two oil at startup?
With respect where did you get these ideas?

 

[dave123]

Ahhhhh help

 

[dwendt44]

40°C is over 100° F.

I'd go by the pour point values.

Once mixed, the two won't separate while truck is standing.
The 0-40 may indeed be thicker at 40°C; that suggests that it stays/gets thicker quicker.

 

[License2ILL]

Steve the vis@ 40c....is lower for 5w. Not by a huge lot...but difinitely more than from 5w to 10w.
What's cafe?? the shortened story of it...ill try to google it.

The oil pan pickup is relatively close to the bottom of the pan in an old school type SBC last time I checked. Well at least low enuff that if i mixed 3 of the heavier and 2 of the lighter...the lighter stuff would not get picked up. That's what I mean....unless of course some one enlightens me with the fact that the 2 would molecularly bond and form a combo instead.... thereby invalidating the whole cheap trick to null.(or maybe not null in that case)

 

[MolaKule]

It's supposed to be:

http://www.bobistheoilguy.com/viscosity-charts/

The oils are NOT going to separate into two viscosities, they are going to mix and form somewhat of an intermediate viscosity.

 

[Steve S]

All oil pan pickups are low in the pans.
The oils will eventually blend together.
CAFE is corporate average fuel economy .That is reason the auto makers are building low friction engines , using thinner oils etc. to boost the max average of the cars they produce.
In FLA any multivisc oil will offer enough "startup protection"

 

[Steve S]

Usually a 40 is thicker than a 30. "forgot to add"

 

[EricJRoy]

FYI, 5w-30's from different manufacturers vary widely in there viscosities, for instance, Pennzoil Ultra is a thinner oil compared to Mobil 1. Mobil 1 0w-40 has a high viscosity index which is desirable because it can do thin when cold and thick when hot better then your average oil, its a nicely engineered product IMO.

 

[TFB1]

Originally Posted By: License2ILL

The oil pan pickup is relatively close to the bottom of the pan in an old school type SBC last time I checked. Well at least low enuff that if i mixed 3 of the heavier and 2 of the lighter...the lighter stuff would not get picked up.


What dream world are you living in???

Once the different weight oils are in the pan they become a homogenic mixture that will not separate...

Basically if you mixed quarts of 10W-30 & 10W-40, your results would be a 10W-35 which would still rated a 30W or 40W depending on the final cSt...

 

[OVERKILL]

This thread makes my head hurt

 

[License2ILL]

Originally Posted By: TFB1
Originally Posted By: License2ILL

The oil pan pickup is relatively close to the bottom of the pan in an old school type SBC last time I checked. Well at least low enuff that if i mixed 3 of the heavier and 2 of the lighter...the lighter stuff would not get picked up.


What dream world are you living in???

Once the different weight oils are in the pan they become a homogenic mixture that will not separate...

Basically if you mixed quarts of 10W-30 & 10W-40, your results would be a 10W-35 which would still rated a 30W or 40W depending on the final cSt...


Its not a dream world cop car lover...either of the two outcomes was possible...mix or not mixed when sitting...I mentioned both since I dont pretend to be a chemical engineer. Pretty fair assumption.

Similar to the ardious math you calculated when you came up with the 35w. For an instance you reminded me of Walter Bishop.
But then i saw your 4x4sedan sign.

 

[TFB1]

If there was only a quart in the pan, about any engine will suck most of it up, leaving only maybe half pint that was unreachable due to the space between the pickup and pan...

You sound like the guy who was convinced the oil he drained from his engine was thicker at the bottom of the bucket, ain't happnin'..

 

[JHZR2]

Because 40C is irrelevant to the "w" rating, which is done at -30 or -35C. There are different curves that connect the -3xC and 100C points, and depending upon the other characteristics of the fluids, they may cross at different temperatures.

 

[229]

M1 0W40 is a high HTHS oil and the other two are low HTHS oils. Given your application and mileage I feel you would be better served staying with your current oil.

 

[fdcg27]

You must remeber that a grade is based upon a range, not a number.
At most temperatures, I would expect a forty to be thicker than a thirty.
The "0W" part only comes into play at very low temperatures, and 104F is not very low.
In an engine needing high HTHS, M1 0W-40 does very well.
If your Camaro can really benefit from an HTHS >3.5, M1 0W-40 is a good and reasonably priced choice.
It may be that GM knew of what it spoke when it recommended a pedestrian 5W-30 for your engine.
That may be all that's required for 200K+ of life.

 

[dwendt44]

Quote:
The oil pan pickup is relatively close to the bottom of the pan in an old school type SBC last time I checked. Well at least low enuff that if i mixed 3 of the heavier and 2 of the lighter...the lighter stuff would not get picked up.


To clarify: Once the engine is started, the oil in the pan gets mixed plenty well; and that takes only a couple of minutes.

 

[GMorg]

All three oils that you listed have the same density. A quart of each will weigh the same. One will not sink below the other.

All motor oils are fully miscible. They will mix -- completely and without issue.

Don't be surprised when a 40 weight grade has a higher viscosity than a 30 weight grade. That will always be true at nearly every practical temperature.

The Winter ratings of 0W or 5W apply to whether or not the oil will stay fluid at very low temperatures. Although it is not exactly accurate, it is sometimes useful to think of the W rating as a surrogate measure of the temperature at which the oil solidifies, or at least become non-pumpable. In other word, the lower the W rating, the lower the temperature at which the oil can be pumped. It is not a measure of viscosity at nearly any other temperature.