5w-20 not the same as 0w-20 when hot?

[Omahaug]

So I think the most common consensus is that:
1. Wherever you use 5w-20, 0w-20 is an acceptable substitute.
2. In most if not all cases 0w-20 meets and excees 5w-20.
3. Mobil 1 for example goes far enough to claim that it will definitely not void your warranty (not that it "may not" they literally said "it will not").
4. That 5w-20 is the same as 0w-20 at operating temperature, the only difference is the 0w vs 5w which means the 0w flows faster and better at cold temperatures.

So then I'm wondering why the viscosity is different on Mobil 1's own website for operating temperature?

Here's Mobil 1 0w-20:
Viscosity, @ 100ºC, cSt (ASTM D445) 8.7
Viscosity, @ 40ºC, cSt (ASTM D445) 44.8

Now here's Mobil 1 5w-20:
Viscosity @ 100ºC, cSt (ASTM D445) 8.9
Viscosity, @ 40ºC, cSt (ASTM D445) 49.8

So the viscosity is less than 5w-20 whether it's hot or cold? Am I reading this right? So when people claim they hear valve train noise when they use 0w-20 are they imagining it? Or does that .2 make a huge difference? I'm beginning to wonder whether I should return these killer crates of 0w-20 I scored at sale (6*1qt Mobil 1 0w-20 for 27.00). I was originally going to go 5w-20 crates but I heard 0w-20 could be substituted for 5w-20...

 

[Nate1979]

Every brand of oil has a little bit different viscosity. They are not all the same. The same goes for the data you list for the two oils in the same brand.

 

[Donald]

There is a range for viscosity. Not every 10W30 has the same viscosity (virgin oil) but they are close and fit into the range to be considered 10W30.

 

[simple_gifts]

"The same" means 20 weight; 20 weight is a RANGE of viscosities.

 

[901Memphis]

Look for SAE J300 revision January 2015.

It specifies all motor oil being a 20 grade fall between 6.9 cSt @100ºC but less than 9.3 cSt @100ºC. This applies to both 0w20 and 5w20 since those are the two most common formulations.

Every manufacturer will formulate a slightly different final KV100 viscosity but currently most of them are staying towards the upper limit with the newer changes.

 

[901Memphis]

http://www.widman.biz/English/Tables/J300.html

Here's the link

 

[Danh]

And, for example, Mobil1's 0w-20 100C viscosity is higher than Pennzoil Pure Plus Platinum's 5w-20 at the same temperature.

 

[Shannow]

Originally Posted By: 901Memphis
http://www.widman.biz/English/Tables/J300.html

Here's the link


The metric that's most related to wear is the "High Temperature High Shear" number.

For a 20, they are typically 2.7ish (the Japanese OEM oils are usually 2.6 target, min spec).

If you have a good HTHS, the KV100 matters little. There's some minor benefit in having lower KV100 for the same HTHS.

 

[Quattro Pete]

Originally Posted By: NoNameJoe
Or does that .2 make a huge difference?

The .2 should make little difference if any. If they are having valvetrain issues, something else is to blame.

 

[901Memphis]

Originally Posted By: Shannow
Originally Posted By: 901Memphis
http://www.widman.biz/English/Tables/J300.html

Here's the link


The metric that's most related to wear is the "High Temperature High Shear" number.

For a 20, they are typically 2.7ish (the Japanese OEM oils are usually 2.6 target, min spec).

If you have a good HTHS, the KV100 matters little. There's some minor benefit in having lower KV100 for the same HTHS.


Yes I agree on comparing oils by HTHSV rather than KV100 where possible.

 

[Omahaug]

Wow that makes sense! Thanks guys, I guess I was just too much of a simpleton to consider that it was a range.

 

[Triple_Se7en]

What vehicle and engine are these two grades connected to?