Why isn't all oil 0W-xx

Status
Not open for further replies.
Joined
Nov 5, 2022
Messages
80
Someone please educate me. After months of research, I still don't understand oil weight and viscosity.

My main question is if 0W-20 and 5W-20 perform the same at operating temperature and most engine wear occurs at startup, why use 5W? Am I not understanding the concept? I have read the webpage "home" multiple times.

Why wouldn't all oil be 0W-xx so cold starts don't wear the motor as much.
 
Joined
Apr 24, 2018
Messages
2,790
Location
Wisconsin
You certainly could now days but you might get shorter oil life in certain cases
0w30 as an example is rather weak

Historically 0w30 didn’t exist so engines were designed around the common oil weights available

Beyond the weight there are also certifications that need to be met.

Now why might you run 10w30 over 0w30?

In my case I have fuel dillusion issues and simple 10w30 Really extends my oil life

Further 10w30 has less VII than 0w30 which makes it less prone to shear down and has stronger TBI numbers.
There is also situations like oil burners and small gas engines where oils with a heavier lower number reduces the propensity to burn
That is why some still use HD30 (no winter rating at all) in their old lawn mowers
 
Joined
Jan 4, 2016
Messages
2,640
Location
704
Someone please educate me. After months of research, I still don't understand oil weight and viscosity.

My main question is if 0W-20 and 5W-20 perform the same at operating temperature and most engine wear occurs at startup, why use 5W? Am I not understanding the concept? I have read the webpage "home" multiple times.

Why wouldn't all oil be 0W-xx so cold starts don't wear the motor as much.
Difference will only exist in extreme cold. Above freezing temps there is no extra wear happening.
But generally speaking: a 5W20 may be more shear stable than a 0W20, due to lower Viscosity Index Improver (VII) additive content. The wider is the spread between the two multigrade numbers, the more VII is necessary. (Unless offset by other chemical wizardry.) Some also speculate that VII additives attribute to varnish buildup in critical high heat areas, like piston rings for example. Which usually leads to sticky/stuck rings and high oil consumption. So in that regard - lower VII content may be helpful.
For manufacturer though - a 5W20 is usually cheaper to make, as 0W20 requires higher quality base oils.

Or you could join us on the dark side and use 0W-40 Euro oils, where VII content may be high, but is greatly offset by increased cleaning abilities, so no extra varnish buildup from burning up polymer VII. On the contrary - Euro rated oils don't just clean up after themselves, but also clean up after previously used less capable oils. Anyways, I'm getting sidetracked, so I'll stop here. Rabbit hole, lemme tell ya...
 
Joined
Jan 4, 2016
Messages
2,640
Location
704
...or I won't stop here lol.
In my opinion, the best thing to do is look at the oil as a whole. As fun as it is to hair split the ingredients or base oils, all of those are just pieces of the puzzle. What matters is how well do all of those puzzle pieces work together in the final picture. As in - what oil shows great performance no matter what it goes into? Some always go for the highest HTHS, others for the lowest pour point, next group for the highest or lowest calcium content in order to get better cleaning or lower chance of LSPI issues, and so on... Lots of hair splitting can be done, but end result is more important in my opinion.
That's why I use oils that meet approvals from my signature below, and I use these oils in every liquid-cooled engine I own and/or maintain. Dozens and dozens of engines. No issues, only improvements in various areas. Lately it's been either Mobil 1 0W-40 or Quaker State 5W-40 for me. Do get Castrol Edge 0W-40 sometimes, but only if M1 or QS aren't available.
 
Last edited:
Joined
Jun 8, 2022
Messages
1,385
Euro rated oils don't just clean up after themselves, but also clean up after previously used less capable oils.
I have been thinking of running one OCI of 0W-40 euro for this reason, then switching to a 10W-30 instead of the factory recommended 5w-30. However I haven't found a 10W-30 that I like yet - they all seem on the thin end of the 30 weight chart for some reason.
 
Joined
Jan 4, 2016
Messages
2,640
Location
704
I have been thinking of running one OCI of 0W-40 euro for this reason, then switching to a 10W-30 instead of the factory recommended 5w-30. However I haven't found a 10W-30 that I like yet - they all seem on the thin end of the 30 weight chart for some reason.
If 1 OCI cleaning is what you need, then HPL Engine Cleaner may be a better option. Euro 0W-40 oils aren't aggressive cleaners. Slow and steady is the name of the game here. But when used continuously - you will see improvements after a few OCIs.
image-25.jpg
 
Joined
Jun 8, 2022
Messages
1,385
If 1 OCI cleaning is what you need, then HPL Engine Cleaner may be a better option. Euro 0W-40 oils aren't aggressive cleaners. Slow and steady is the name of the game here. But when used continuously - you will see improvements after a few OCIs.
View attachment 127347
I don't really need any cleaning - engine is perfect. Was going to do it just because, and because the 0w-40 would for sure not hurt anything, and this site has a way of getting you to overthink things.
 
Joined
Jun 3, 2012
Messages
1,292
Location
Bremerton, WA
0W-xx is a weaker formulation with extra viscosity improver, and more expensive to produce.

0W-xx is a viscosity rating, not a flow rating, and not a protection rating.
 
Joined
Oct 22, 2009
Messages
8,145
Location
Wet side WA
Someone please educate me. After months of research, I still don't understand oil weight and viscosity.

My main question is if 0W-20 and 5W-20 perform the same at operating temperature and most engine wear occurs at startup, why use 5W? Am I not understanding the concept? I have read the webpage "home" multiple times.

Why wouldn't all oil be 0W-xx so cold starts don't wear the motor as much.
Why use 5W well because sometimes its the one on sale and here on the wetside it never gets cold enough you need 0W.
 
Joined
Mar 13, 2013
Messages
1,187
Location
UK
0W-xx is a weaker formulation with extra viscosity improver, and more expensive to produce.
That's not necessarily true. It depends as much on the base oils as anything else - if you use higher VI base oils you can get wider viscosity spread without the need for excessive VII use. This does come at a cost, but can be a better oil.
 
Joined
Dec 26, 2005
Messages
23,662
Location
Upper Midwest
That's not necessarily true. It depends as much on the base oils as anything else - if you use higher VI base oils you can get wider viscosity spread without the need for excessive VII use. This does come at a cost, but can be a better oil.
Agreed. The whole notion that a particular winter rating makes an oil “weak” (whatever that means exactly) is silly. Oils are formulated differently and carry different licenses, specifications and different approvals. That’s what determines performance not some blanket statement about the winter rating.
 
Joined
Dec 30, 2006
Messages
29,483
Location
Dallas,Tx USA
If 1 OCI cleaning is what you need, then HPL Engine Cleaner may be a better option. Euro 0W-40 oils aren't aggressive cleaners. Slow and steady is the name of the game here. But when used continuously - you will see improvements after a few OCIs.
View attachment 127347
I wonder which M1 formula this is? Vanilla, EP, or HM? I will say the cleanest engines on this site are all M1 engines.👍
 
  • Like
Reactions: wlk
Joined
Feb 15, 2003
Messages
13,426
Location
Jupiter, Florida
It is interesting to see that the speculation about 0W-xx oils not being as shear stable is borne out in (shared transmission) motorcycle use. Motorcycle transmissions tend to be tough on oils. Almost universally, an oil with a wide spread, such as 5W-50 or 0W-40 will be far less shear stable in motorcycle use.

Amsoil makes a product for motorcycles 0W-40 and is specifically designed for ATV's/powersports. Not for high performance motorcycles.

In the end, motorcycle guys get more shear stable results with higher base oil viscosity. Both M1 10W-40 and Amsoil 10W-40 synthetic motorcycle oils are exceptionally shear stable in shared transmission motorcycle use. The HTHS numbers are often better with the more robust oils. M1 10W-40 motorcycle oil has an HTHS of 4.15. M1 0W-40 has an HTHS of 3.6 (by memory) and shears down considerably during use.

In other words, one of those oils should provide a considerably higher level of protection under extreme high temp and high load conditions.

Interestingly, there are 5W-30 oils with higher HTHS numbers than a typical OW-40. I know which one I'd use, the 5W-30.
 
Joined
Dec 26, 2005
Messages
23,662
Location
Upper Midwest
It is interesting to see that the speculation about 0W-xx oils not being as shear stable is borne out in (shared transmission) motorcycle use. Motorcycle transmissions tend to be tough on oils. Almost universally, an oil with a wide spread, such as 5W-50 or 0W-40 will be far less shear stable in motorcycle use.

Amsoil makes a product for motorcycles 0W-40 and is specifically designed for ATV's/powersports. Not for high performance motorcycles.

In the end, motorcycle guys get more shear stable results with higher base oil viscosity. Both M1 10W-40 and Amsoil 10W-40 synthetic motorcycle oils are exceptionally shear stable in shared transmission motorcycle use. The HTHS numbers are often better with the more robust oils. M1 10W-40 motorcycle oil has an HTHS of 4.15. M1 0W-40 has an HTHS of 3.6 (by memory) and shears down considerably during use.

In other words, one of those oils should provide a considerably higher level of protection under extreme high temp and high load conditions.

Interestingly, there are 5W-30 oils with higher HTHS numbers than a typical OW-40. I know which one I'd use, the 5W-30.
Very few automobile engines have a problem with mechanical shear.
 
Joined
Sep 16, 2003
Messages
3,969
Location
Austin, TX MSA
10w30 can be made with Group II basestock. It should be cheaper theoretically but it isn't due to marketing.

10w30 works great in my tired engine that calls for 5w20, at least down here in Texas.
 
Joined
Jul 12, 2012
Messages
7,327
Location
Caldwell Idaho
What gives you the idea that a 0w-xx produces less wear on startup with respect to the proper oil viscosity at cold start temps on start up. Start up wear is a combination of things .
 
Last edited:
Status
Not open for further replies.
Top