Help with dilema what is the difference between 5W and 10W-30

[Rick]

I mean they are both 30 weight when warm right?
So what is the difference?

 

[mountravlr]

The 5W and 10W have to do with the oils behavior in cold temperatures: Cold Crank Simulator Apparent Viscosity @ -25C, cP ASTM D2602 in the range of <2310 for instance, 5W or 1840 10W AND Borderline Pumping Temperature ASTM D3829 for instance -47F 5W or -42F 10W AND Pour Point, for instance -67F 5W or -54F 10W. These are published specs for Amsoil 5w30 and 10w30. Other brands should have similar characteristics. And yes they are 30 weight oils at operating temps.

 

[TallPaul]

quote:

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Originally posted by Rick:
I mean they are both 30 weight when warm right?
So what is the difference?

---

As a rule, the 10w30 is going to have a thicker (higher viscosity) base oil than the 5w30. The base oil is what the company started with before putting all the additives, including viscosity index modifiers, into the mix.

 

[97tbird]

[/qb][/QUOTE]As a rule, the 10w30 is going to have a thicker (higher viscosity) base oil than the 5w30. The base oil is what the company started with before putting all the additives, including viscosity index modifiers, into the mix. [/QB][/QUOTE]
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BUT when you compare Cst @ 100C for Motrcraft 5w30 and 10/30, the 5w30 has the higher cSt@100c, and the 10/30 has a lower value...I don't know how old that data, though(MC website!)

wonder why's that?

 

[TallPaul]

quote:

---

Originally posted by 97tbird:
BUT when you compare Cst @ 100C for Motrcraft 5w30 and 10/30, the 5w30 has the higher cSt@100c, and the 10/30 has a lower value...I don't know how old that data, though(MC website!)

wonder why's that?

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I have noticed that too. Of course that is the 100C viscosity with the viscosity index improvers included. Not sure what is going on here. Maybe they start higher expecting more viscosity loss on the wider spread 5w30. Guess we need one of the site experts: Terry, MoleKule?

 

[harrydog]

quote:

---

Originally posted by TallPaul:

quote:

---

Originally posted by 97tbird:
BUT when you compare Cst @ 100C for Motrcraft 5w30 and 10/30, the 5w30 has the higher cSt@100c, and the 10/30 has a lower value...I don't know how old that data, though(MC website!)

wonder why's that?

---

I have noticed that too. Of course that is the 100C viscosity with the viscosity index improvers included. Not sure what is going on here. Maybe they start higher expecting more viscosity loss on the wider spread 5w30. Guess we need one of the site experts: Terry, MoleKule?

---

Right. Maybe it's that the 5w30 has more VII while the 10w30 has fewer or even none. That could cause the 5w30 to be thicker when hot, but it might not be as shear/heat stable over the long run either.
Just a thought.

 

[TallPaul]

You can always thicken up (or should I say boost the 100C viscosity of) that 10w30 with a quart of 10w40 thrown in if you want.

 

[haley10]

Let me throw a fly in the ointment if I may. Mobil 1 0w30 is their thickest 30 weight @ 100C.

 

[427Z06]

With dinos and the wider spread syns, think base oils, pour point depressants and viscosity index improvers.

 

[Hirev]

There is a range in what is acceptable in a 30 weight This might help.

SAE
Viscosity
Grade Viscosity
at 100°C
Min ~~~ Max
0W 3250 3.8
5W 3500 3.8
10W 3500 4.1
15W 3500 5.6
20W 4500 5.6
25W 6000 9.3
20 5.6 30 9.3 40 12.5 50 16.3 <21.9

 

[Ray H]

I agree with your "just a thought" analysis, harrydog. Either viscosity range will work, but, presuming conventional petroleum-based blends, if I lived in an area subject to high ambient temperatures, I'd go with the 10w30 as a safety margin against excessive shearing down over the OCI.