Thinner oils and higher wear

[Shannow]

Originally Posted By: Pontual
But cushion for dirty particles is important, ohw, come on!!


It's a classic design parameter, you want the filter to be removing particles that are larger than the smallest clearance in the equipment being lubricated.

Otherwise the dirt particles get trapped (filtered) at the point that the clearance is smaller than the particle.

If the filter is good for 5um, and the oil film hot and running is 0.5um, the circulating dirt particles can't fit into the MOFT region of the bearing, and will build up causing wear...as I said previously, and silk confirmed through his observation, the old thick white metals allowed these particles to embed in the bearing materials, and stay out of harm's way.

It's a fact.

Now in IC engines, that aren't run steady state for 8,760 hours a year (one of my turbines did around 12,000 hours without a shutdown)...fortunately there are cyclic loads, and start-ups.

During a start-up, the oil film is considerably thicker than hot steady state, so any of these particles has a good change of being flushed back into the sump...

 

[bbhero]

Man, you are the Professor. If I happen to win a huge lottery and I open up a new business. I am going to attempt to hire you. Just because of how strong abilities you possess such as you smart, insightful and the ability to teach.
That having been said... I really enjoy reading your posts. Really very helpful and well stated

 

[Shannow]

bbhero,
just checked with my wife, and she wants to know when this lottery thing is happening...we'd move to the US, no probs.

 

[fdcg27]

Let's say that thinner oils really do allow more engine wear than do thicker grades.
How much more?
This could be measured and quantified, which would then allow us to judge whether this excess wear is of enough significance to be of any concern.
Anyway, the life of the engine powering it is rarely the limiting factor in the useful life of a passenger car or light truck.
If greater engine life won't bring any increase vehicle life, then what would be the point?
Over the years and miles, everything wears and eventually breaks. Any vehicle can be driven any huge number of years and miles as long as the owner is willing to keep fixing it.
Once you start to significantly exceed vehicle design life, a host of things will start to require attention, with the engine itself probably the least of your worries.
This has nothing to do with any mendacious motives on the part of vehicle manufacturers either.
Any maker could build vehicles with significantly longer design life. This would also result in significantly higher costs which would then be reflected in selling prices.

 

[Shannow]

true, but when I have suggested that a reduction in potential engine life is justified by the fuel savings and in not having an engine that outlives the vehicle by an average factor of 2 or 3, I get called a liar.

It's a fair balance, as long as every player is aware that it's a balance.

Thin oils aren't there to make your engine last longer, which is the posit that some here are pushing.

 

[wemay]

As I've said before. Anyone can find logical, scientific explanations to support their side of the argument using various online sources.
-particles larger than oil film = thicker is better
-lower viscosity circulating faster at startup = thinner is better.
Etc...........

 

[Shannow]

Originally Posted By: wemay
As I've said before. Anyone can find logical, scientific explanations to support their side of the argument using various online sources.
.
.
-lower viscosity circulating faster at startup = thinner is better.


have at it wemay...please post a logical, scientific explanation (not Doc's 101, or CATERHAM's unsubstantiated posits)

(the benefits in industry standard warm-up tests like the sequence IVA would nail my coffin closed)

 

[buster]

Originally Posted By: Shannow
Originally Posted By: buster
For startup wear, lower viscoisty is better.


buster, you are going to have to provide evidence for that claim.

e.g. how thinner oils protect better in industry standard warmup wear tests like the sequence IVA...

not just the Doc's and CATERHAM's koolaid...some evidence.


Good point.

 

[wemay]

Oh no...

The reason for my post was not meant to get pigeonholed into taking a side. The reason for my post was to show there are always good reasons given for each perspective. Articles from reputable publications expressing the merits of either side may not be scientific, but for a layperson like me, are an easier read. Remember, i always try to approach these topics from the perspective of the 'common man' not necessarily one verse in understanding all the chemistry. Im learning though Shannow.

 

[badtlc]

Originally Posted By: Pontual


"Thinner oils don't give enough cushion for particles trapped in part clearances."




This statement is obviously plausible. But so what? OK, maybe I missed it, but where are these values? What is the oil film thickness measurement for these thin oils? How big are the clearances? What are the particle sizes? Where is the data saying it is an issue?

You can always make blanket statements that are true but not applicable. That means very little.

 

[Brigadier]

I was under the impression that most 'start up wear' occurs due to the acids that are formed as byproducts of combustion once the engine is shut off and allowed to cool.

https://books.google.com/books?id=0SoDAA...ids&f=false

http://www.truckinginfo.com/article/story/2014/08/chevron-warns-about.aspx

 

[il_signore97]

Originally Posted By: Brigadier
I was under the impression that most 'start up wear' occurs due to the acids that are formed as byproducts of combustion once the engine is shut off and allowed to cool.

https://books.google.com/books?id=0SoDAA...ids&f=false

http://www.truckinginfo.com/article/story/2014/08/chevron-warns-about.aspx



^This is something I've pointed out in many of these threads before. The fact that most of the start-up wear is actually chemical/corrosive wear has absolutely nothing to do with lubricating oil, unless it's grossly misapplied (as Shannow has stated many times as well). Also, we can't ignore the fact that many parts of the engine (such as pistons for example) do not "fit" into their respective places well until warm, when all of the clearances are within design spec at operating temperature.

There have been some SAE papers authored about this, but since I'm not an SAE member any more, I can't look them up. Any current SAE members on here feel free to dig them up if you feel like some good reading

 

[wemay]

Originally Posted By: badtlc
Originally Posted By: Pontual


"Thinner oils don't give enough cushion for particles trapped in part clearances."




This statement is obviously plausible. But so what? OK, maybe I missed it, but where are these values? What is the oil film thickness measurement for these thin oils? How big are the clearances? What are the particle sizes? Where is the data saying it is an issue?

You can always make blanket statements that are true but not applicable. That means very little.



I think we all agree that the trend towards lower viscosity is driven by fuel economy (CAFE). But to ride the coat-tails of badtlc here, does this mean any measurable increase in wear that results in shorter engine life? Could it not be that since this trend is in effect, the lower viscosity oils are the most heavily researched and advanced oils because they need to be?

Let me pose a question of application here:

Warranty aside...
A 0w20 would not be suitable in an application calling for 0w40
Would the contrary be true?

 

[Pontual]

Yes, me too, in spite of not being an purely scientific article, the argumets are fawless, but some Anecdotes always add. "I use, people use and people are using their vehicles for 200k+ miles, no problems".
Ok,
Cofee wins!

 

[Pontual]

Originally Posted By: badtlc
Originally Posted By: Pontual


"Thinner oils don't give enough cushion for particles trapped in part clearances."




This statement is obviously plausible. But so what? OK, maybe I missed it, but where are these values? What is the oil film thickness measurement for these thin oils? How big are the clearances? What are the particle sizes? Where is the data saying it is an issue?

You can always make blanket statements that are true but not applicable. That means very little.



Ok, now explaining like to my very minor age soon. I'll paint the statments, with common knowledge spread all over this forums. Nay sayers will keep coming, I know.

1) most spin oil filters are 25 microns absolute collection, so anything below 25 microns will circulate eventually;
2) parts clearance are 7 to 25 microns wide, the exact sizes of most particles that the filter won't catch;
3) oil films under load, are smaller than the gap between parts, obviously, with variations going from 3 micros to 25 microns (just look at the figures in the article) within the play of parts. So, anything above 3 microns has potential to scratch/embbed/detach pieces from the parts, giving birth to new debries thats would make a geometric wearing causes like virus reproduction;
(...)

That's why I use short OCI with decantation (knew here as Mobil2), thicker Oil and magnets on filter and drain plug, to get iron debries from 3 to 25+ micros, out of circulation, since after sand, the most havoc comes from Fe particles.

 

[Pontual]

Originally Posted By: Brigadier
Originally Posted By: FutureDoc
Originally Posted By: Pontual
Ok, I won't stretch my argments, and I take the above article as a Bow. But for me the tendence is to "people - you know who - saying to you like "F'up your engine to save gas and the environment".
Good for the world, that too many of us contribute conscientiously, not as braiwashed.


just like the people who roll some coal...

CAFE is fiscal responsibility. It is fuel economy, not efficiency or an act of environmentalism. The point is to use less fuel so we are not handing Benjamins to countries that we don't like a lot. So that when those countries cut of the taps, our economy does not tank because we want our engines big, weak, and thirsty. Lower viscosity oil is the the private-sector solution (ie a cheap way) for them to meet a need. The other solution is to jack-up the fuel tax

Lets bump up the Federal tax from 19 cents to a buck fifty...and then sit-back and watch the 0wXX fly off the shelf.



Oh Puleeeeze. That is more a function of America hating politicians not allowing us to be energy independent that ruining your engine with 0W0 oil.

Less dependency is good. Everybody need to cooperate.

 

[Gokhan]

What is forgotten in this discussion is that conventional 5W-30 and even many synthetic 5W-30 oils shear to 5W-20 anyway; so, there is really not much difference in viscosity between 5W-20/0W-20 and most 5W-30 oils.

5W-20/0W-20 oils that are commercially available are very close to xW-30 weight and they are more shear-stable than xW-30. Any car that can tolerate 5W-30 should be able tolerate 5W-20/0W-20.

The only exceptions are ACEA A3/B3(/B4) xW-30 oils. These are what I call "xW-35" oils and are closer to xW-40 than xW-30 in weight. Neither xW-20 nor regular xW-30 should be used if such "xW-35" is the minimum viscosity specified.

 

[Pontual]

Originally Posted By: Shannow
Originally Posted By: Pontual
But cushion for dirty particles is important, ohw, come on!!


It's a classic design parameter, you want the filter to be removing particles that are larger than the smallest clearance in the equipment being lubricated.

Otherwise the dirt particles get trapped (filtered) at the point that the clearance is smaller than the particle.
(...)
During a start-up, the oil film is considerably thicker than hot steady state, so any of these particles has a good change of being flushed back into the sump...


Yes, the classic design parameter of bypass valve filter, is to open up at higer pressure (cold start and warmups and even at many WOT instances) sending all the dirty it cought back to the sump. Will try to get them again. I agree, but a smashing oil pump, liner, crank and acessories will mill the big 50-100 microns ex trapped in filter debries, down to smaller (any size you want) and harming chunks. It is a cycle that never ends, since as you said, every day, you start the engine cold and shut it down.

The dilemma is: or you have a lazy filtration with lots of burst in bypass, or your have a filter media tearing up. Spin on fullflow of 5 microns absolute is legend, practically impossible.

 

[il_signore97]

Originally Posted By: Gokhan
What is forgotten in this discussion that conventional 5W-30 and even many synthetic 5W-30 oils shear to 5W-20 anyway; so, there is really not much difference in viscosity between 5W-20/0W-20 and most 5W-30 oils.

5W-20/0W-20 oils that are commercially available are very close to xW-30 weight and they are more shear-stable than xW-30. Any car that can tolerate 5W-30 should be able tolerate 5W-20/0W-20.

The only exceptions are ACEA A3/B3(/B4) xW-30 oils. These are what I call "xW-35" oils and are closer to xW-40 than xW-30 in weight. Neither xW-20 nor regular xW-30 should be used if such "xW-35" is the minimum viscosity specified.



This is a strawman argument that is really not true anymore in MOST applications (yes, there will always be those few engines that can grind any oil down a grade). But in general, today's synthetic 5W30 oils are generally very robust, and shear stable. So your above statements are not entirely correct.

 

[FutureDoc]

Originally Posted By: Pontual
Less dependency is good. Everybody need to cooperate.


Yeah, but most Americans would spaz out of we took the Brazilian fuel model. Some folks go out of their way to avoid E10, let alone forcing folks onto E18-E25 (and some would have a stroke if we went E100. You don't need CAFE if we grew 50% of our fuel.