Dangers of low viscosity oils a problem waiting to happen?

[nascarnation]

I'm sure veteran members here will recall when it was predicted that the roadsides of America would be lined with failed vehicles caused by a certain brand of orange colored oil filter. Now that those have all finally been towed away, we can move on to cleaning up the mechanical carnage caused by 0W8 oils.

 

[Bill7]

There is no insanity and I have proved it pulling 5,000 pounds up 9,000 foot mountain passes in 90plus degree weather running 0w/20. Don't think a Corolla will see those conditions....

There is nothing wrong with 20 weight oil. Those Ford LTD taxis with 400k+ miles on their odometers that seem to still be servicing small towns in the US are all speced 5W-20.

I believe 20 weight oil is adequate, 30 weight oil in Optimal. But since the cost is the same, I prefer 30 weight with it's higher HTHS.
Most countries in the world specify 30 weight as the lowest allowable viscosity in their owners manuals.

 

[PandaBear]

0w16 and 0w8 are usually for engine with variable displacement oil pump, so they would likely have more flow and oil film when the rpm is low and load is high. If your car spec for it you don't need to worry.

 

[factorytuned2012]

GF6-B makes thin oils up to snuff

 

[OilUzer]

There is nothing wrong with 20 weight oil. Those Ford LTD taxis with 400k+ miles on their odometers that seem to still be servicing small towns in the US are all speced 5W-20.

I believe 20 weight oil is adequate, 30 weight oil in Optimal. But since the cost is the same, I prefer 30 weight with it's higher HTHS.
Most countries in the world specify 30 weight as the lowest allowable viscosity in their owners manuals.

I like your post but what happened to the manly 40?

 

[nascarnation]

Engines are specifically designed to be compatible with the thinner oils. An example of one change is that bearing surfaces on the crank shaft are larger in engines that are designed for 0W-16 or 0W-8 vs a similar engine designed for 5W-30. Although the oil film may be weaker on that bearing surface, there is a larger surface area bearing the load to make up for it. You can still run a thicker oil in the new engines, but you shouldn't run the thinner oils in an older engine.

That seems counter-intuitive. Adding cost and weight seems like it would offset any gains from the low viscosity lube.

 

[wsar10]

I call this debate to order and move that we recognize the Thickies!

Long live the "Thickies"!!

 

[IndyIan]

Isn't the HS/HT viscosity the main factor in predicting oil film thicknesses in a bearing? With small particles, they are mostly fine as long as they don't get pinched in a bearing. But if the oil film is too thin, and particles to start getting pinched, I don't think additives can do a whole lot?
So I guess if you've got a very good oil filter, and air filter, these thin oils are fine, but if something starts to go wrong, I would assume the thin oils have literally less cushion to deal oil particle contamination?

 

[The Critic]

0w16 and 0w8 are usually for engine with variable displacement oil pump, so they would likely have more flow and oil film when the rpm is low and load is high. If your car spec for it you don't need to worry.

These engines also often contain specialized coatings to address wear issues:

https://www.drivparts.com/en-eu/brands/glyco.html

 

[kschachn]

These engines also often contain specialized coatings to address wear issues:

https://www.drivparts.com/en-eu/brands/glyco.html

Plus flow never lubricated a bearing. The variable pressure oil pumps are there to reduce energy requirements. They don't save the day with low viscosity oils.

 

[MolaKule]

0w16 and 0w8 are usually for engine with variable displacement oil pump, so they would likely have more flow and oil film when the rpm is low and load is high...

Just to clarify for journal bearings, it is the oil "wedge" that develops soon after journal motion upon startup and subsequently an oil film develops.

The oil pressure does not "float" the bearings but oil pressure results in oil flow to cool the bearings via 'side' leakage. Of course in many engines, we also have oil squirters that shoot oil to the underside of the piston for additional cooling.

"...Let's look at this in stages.

The oil wedge between the bearing and journal will not be present in the first few milli-seconds of startup, so no MOFT, therefore what you need is an anti-wear compound that resists startup wear until the pressure has developed in the oil wedge, which is a transition from Boundary Lubrication to Hydrodynamic Lubrication.

Crystals of various hexagonal Boron nitrides (h-BN), or Titatanium oxides (TiO2), or Tungsten Nitrates/Nitrides suspended in an ester tend to make good cold start anti-wear compounds.

The same goes for cam surfaces; the above compounds act as 'cool-temp' anti-wear agents until things heat up..."

Post in thread 'What is the best oil ingredient to protect against cold start wear?'

Sep 14, 2020

Let's look at this in stages.

The oil wedge between the bearing and journal will not be present in the first few milli-seconds of startup, so no MOFT, therefore what you need is an anti-wear compound that resists startup wear until the pressure has developed in the oil wedge, which is a transition from Boundary Lubrication to Hydrodynamic Lubrication.

Crystals of various hexagonal Boron nitrides (h-BN), or Titatanium oxides (TiO2), or Tungsten Nitrates/Nitrides suspended in an ester tend to make good cold start anti-wear compounds.

The same goes for cam surfaces; the above...

• MolaKule

• 

Post #16

https://www.tribonet.org/wiki/journal-bearing/

https://rotorlab.tamu.edu/me626/Notes_pdf/Notes07 Thermal Anaysis JBs w examples.pdf

https://gennonotes.github.io/EMEC-4438/EngDes2-W8.pdf

https://dyrobes.com/wp-content/uplo...s-Characteristics-and-Applications_linked.pdf

 

[DirectRejection]

@MolaKule...

Thank you for providing applicable and interesting information for the subject at hand in this thread.

There is frankly a paucity of that at BITOG vis-a-vis very thin oils.

Prior to the introduction of GF-6 oils to market, ILSAC spent years developing tests that substantiated that very thin oils would hold up, when used judiciously.

It is about basestocks, chemicals and reactions, not just viscosity.

Faith in physics...and chemistry.

 

[TomYoung]

There is nothing wrong with 20 weight oil. Those Ford LTD taxis with 400k+ miles on their odometers that seem to still be servicing small towns in the US are all speced 5W-20.

I believe 20 weight oil is adequate, 30 weight oil in Optimal. But since the cost is the same, I prefer 30 weight with it's higher HTHS.
Most countries in the world specify 30 weight as the lowest allowable viscosity in their owners manuals.

20 weight is adequate, 30 weight optimal. Gotcha.

 

[spasm3]

These engines also often contain specialized coatings to address wear issues:

https://www.drivparts.com/en-eu/brands/glyco.html

I wonder if the oems are using nitrided crankshafts.

 

[Pete in PA]

I for one will stop at 5w-30. Have a 24 Chevy Trax. calls for 5w-30. With absolutely no change in the engine, 25 now calls for 0W-20.
Not only that, but talked to my dealer and they said they'd be putting in 0W-20 in my 24!! No free oil change for me.

 

[kschachn]

I for one will stop at 5w-30. Have a 24 Chevy Trax. calls for 5w-30. With absolutely no change in the engine, 25 now calls for 0W-20.
Not only that, but talked to my dealer and they said they'd be putting in 0W-20 in my 24!! No free oil change for me.

Ask them not to. That’s what I did for my Tiguan when it was new and had free oil changes. They used 504 00 instead of 508 00.

 

[DirectRejection]

Of course we do know the meaning of the term "back spec'd" and the distinction between SP and SN.

 

[kschachn]

Of course we do know the meaning of the term "back spec'd" and the distinction between SP and SN.

But API licenses are forward-specified.

 

[hrv]

I'm sure veteran members here will recall when it was predicted that the roadsides of America would be lined with failed vehicles caused by a certain brand of orange colored oil filter. Now that those have all finally been towed away, we can move on to cleaning up the mechanical carnage caused by 0W8 oils.

O that still goes on on this site....

 

[4WD]

I think of bearing hydrodynamics like a skim board - once speed is lost the board might touch the sand …