Understanding viscosity and sheer strength of different oils

[george1122]

There are additives in oil that makes multi-temperature oil good for hot and cold weather like 0W20, 5W30, 10W30, 10W40, etc. I have the impression the base or base stock oil is the first number (correct me if I'm wrong) and additives give the oil the second number, for warm/hot weather of course.

Does oil with smaller differences between the numbers help the oil overcome viscosity and sheer strength breakdown due to the base oil being thicker. Is that true? If it is, how much of a difference is there?

I know the second question above is difficult to answer. Im trying to get an idea to have a better understanding and possibly switch from the current 5W30 to 10W30 in the future when my powertrain warranty runs out. The American manual does not recommend anything thicker than 5W30 but foreign manuals say the same vehicle can take thicker oil.

 

[Plumb Bob]

Thread 'SAE J300 Viscosity Grades' https://bobistheoilguy.com/forums/threads/sae-j300-viscosity-grades.389290/

 

[JavierH19]

The additives as in the detergent or dispersants have no influence on viscosity unless we include the pour point depressants and viscosity modifiers that are sometimes but not always pre-included in the additive package that is then mixed with the base

The two aforementioned affect the winter rating not the grade. You could blend an oil to be a 0w-40 with the sufficient quantity of the two required but have it be devoid of detergent or anti wear additives for whatever reason and still be a 40 grade. But you could also blend an oil without either of the two and instead of being a 0w-40 it might be a 25w-40 without any help. If it's made of Pao or GTL it might be able to be a 20w-40 without the need of either the two.

 

[calif916]

As I understand it, the larger the spread between the w and the at temperature flow, the more prone to sheer it is.
For instance 5W-20 would sheer less than 0W-20.
That would mean that 0W-40 is going to sheer more than 10W-40.
What's most important is what grade of oil do you really need.
I live in California and it seldom freezes. I have an older truck. 10W-30 works well for me.

 

[kschachn]

As I understand it, the larger the spread between the w and the at temperature flow, the more prone to sheer it is.
For instance 5W-20 would sheer less than 0W-20.
That would mean that 0W-40 is going to sheer more than 10W-40.
What's most important is what grade of oil do you really need.
I live in California and it seldom freezes. I have an older truck. 10W-30 works well for me.

View attachment 337246

Going from thread to thread making the same post?

 

[calif916]

It's a different post.
Just the truck is the same.

 

[Astro14]

It's a different post.
Just the truck is the same.

Same post, same misconceptions. Please go read as I asked. PM me when you finish it. Thanks.

 

[JAG]

Same post, same misconceptions. Please go read as I asked. PM me when you finish it. Thanks.

Are there new forum rules that I’m unaware of allowing moderators to assign homework and try to hold the assignees accountable?

 

[kschachn]

Are there new forum rules that I’m unaware of allowing moderators to assign homework and try to hold the assignees accountable?

It’s a welcome notion.

 

[Astro14]

Are there new forum rules that I’m unaware of allowing moderators to assign homework and try to hold the assignees accountable?

We don’t discuss moderation decisions in public, there is a policy against that, however, I’ve sent you a PM

 

[Tricknologist]

Are there new forum rules that I’m unaware of allowing moderators to assign homework and try to hold the assignees accountable?

There's a saying: jannies do it for free