Why use thicker oil?

[1sttruck]

"Their are too many other oil-related variables beyond virgin HTHS and kinematic viscosities.

All this and more is right here, written by industry experts: http://books.google.com/books?id=Fu-99Mc...result#PPA45,M1"

That book is two decades old now. See below for a decade old paper and another less than that...

http://www.sae.org/technical/papers/980702

Properties of Engine Bearings Lubricated With Low Hths Viscosity Oil
Document Number: 980702
Date Published: February 1998
Abstract: Properties of engine bearings were investigated with different bearing materials and different HTHS viscosity oils by means of both an engine test and a rig test.

The rig test well simulated the bearing wear which occurred in the engine test. Lead-bronze bearings with lead-tin-indium overlay gave the least amount of wear in operating under high-speed and heavy-load conditions even with low HTHS viscosi Aluminum bearings without overlay gave good wear resistance in the case of no seizure occurrence. The wear amount of bearings were well correlated with HTHS viscosity, not with kinematic viscosity.



ftp://ftp.astmtmc.cmu.edu/docs/diesel/hdeocp/minutes/2001/hdeocp.2001-06/0601ATT18.PDF
Shear Stability and the Relationship to Heavy Duty Engine Lubricants

(pg 3)
HTHS viscosity relates to oil film thickness in high shear conditions
– Bearing film thickness and wear
– Liner wear
– Engine tests do not represent full range of potential conditions which could be encountered in the field

Fresh oil HTHS viscosity and used oil HTHS viscosity
give similar relationship to wear


(pg 4)
Relationship of HTHS viscosity to Cylinder Liner Wear
Relative Liner Wear Rate, μm/h
HTHS Viscosity, cP
Fresh Oil HTHSV R2 = 0.8515
Used oil HTHSV R2 = 0.8291

 

[PT1]

My experience has led me to believe that the most important factor in long engine life is the following:

1. draining factory fill at 1/2 the manufacturers OCI to remove breakin debris and unwanted assembly materials (exception:Honda)
2. following OEM oil viscosity recommendation and OCI
3. replacing air filter often and cleaning PCV often
4. Luck of the draw on assembly day at the factory where your engine was assembled
5. I base this theory on watching multiple friends who have absolutely NO mechanical ability log 300,000+ miles on engines that had nothing but WalMart ST dino oil & filter & air filter changes every 3-4000 miles.
6. I have also had 2 GM and 1 Mazda engines bought new and maintained fanatically begin to fail within 20,000 miles while run on the best synthetic oil.

So, I think it is all just a carp shoot.

 

[Gary Allan]

Quote:

ftp://ftp.astmtmc.cmu.edu/docs/diesel/hdeocp/minutes/2001/hdeocp.2001-06/0601ATT18.PDF
Shear Stability and the Relationship to Heavy Duty Engine Lubricant


Hmmmm ...that document appears to deal exclusively with HD diesels there ....

Got anything on anything that isn't in some assumed max stressed state "by design"??

That is, I don't understand how you can template that data over the vast span of lubrication environments.

When all of lubrication looks like a nail ..you always use a hammer to lube it.

Viscosity does offer more protection ...from states that 99.99% of those rolling on the road will never see 99.99% of the time (fake figures for demonstration purposes only - no oil or engine was harmed in this rhetorical rant)

 

[Liquid_Turbo]

Originally Posted By: PT1
My experience has led me to believe that the most important factor in long engine life is the following:

1. draining factory fill at 1/2 the manufacturers OCI to remove breakin debris and unwanted assembly materials (exception:Honda)
2. following OEM oil viscosity recommendation and OCI
3. replacing air filter often and cleaning PCV often
4. Luck of the draw on assembly day at the factory where your engine was assembled
5. I base this theory on watching multiple friends who have absolutely NO mechanical ability log 300,000+ miles on engines that had nothing but WalMart ST dino oil & filter & air filter changes every 3-4000 miles.
6. I have also had 2 GM and 1 Mazda engines bought new and maintained fanatically begin to fail within 20,000 miles while run on the best synthetic oil.

So, I think it is all just a carp shoot.

What cars do your friends run? What GM and Mazda engine?

 

[1sttruck]

"Viscosity does offer more protection ...from states that 99.99% of those rolling on the road will never see 99.99% of the time"

Then why don't people racing use thinner oils than what they're typically using as it will provide better performance ? Why don't makers recommend thinner oils than what they're using as it will provide better fuel mileage ? Why didn't Europe move to thinner oils decades ago as they've always lived with much higher fuel costs ? It's because it's known the world over, perhaps bitog excluded as 'a geographical oddity', that there is a relationship between viscosity (hths) and wear, regardless of what people prefer to use.

 

[Gary Allan]

Quote:
Then why don't people racing use thinner oils than what they're typically using as it will provide better performance ?


Because their racing. Are you racing? Am I? Not the last time I checked.

..but ..while we're at it.. why does Chevrolet spec a 30 weight for their production sports car? Do they seize?

Quote:
Why don't makers recommend thinner oils than what they're using as it will provide better fuel mileage ?

..because my experiments with 0w-10 oils isn't complete and GM, Ford, and Chrysler are chomping at the bit for Bruce to get a final blend? I give up ..why?

Quote:
Why didn't Europe move to thinner oils decades ago as they've always lived with much higher fuel costs ?


This is disingenuous. Euro spec's long drains. If you'll note on most of your domestics, the factory length of service is 5k. It's 5k for a Toyota ..it's 5k for a Ford. Hardly the 18km of the Euro's. The unspoken truth ..that is unless the rolling fleet of 5w-20 users is grinding to a halt in mass droves as we post here, is that lighter oils are FINE over limited durations of use.

You cite the use of lighter oils to qualify for NASCAR races as some indication that increased wear is occurring ..and therefore they don't use them for the main event. It is just as true that the lighter oils cannot go the 500 mile distance and be viable. That is, if they could pit every 5 laps and just use accumulated times in a flying start ..you would see JiffyLube City in the pits. Races would truly be won or lost in the pits.

Quote:
It's because it's known the world over, perhaps bitog excluded as 'a geographical oddity', that there is a relationship between viscosity (hths) and wear, regardless of what people prefer to use.


..and I still ask for the legions of seized or tired engines that should be amassing ..everywhere ...just where are they? In Texas? Florida? Alabama? Are junkyard teeming with 2002 and later models of virtually all makes and models?

 

[PT1]

Originally Posted By: Liquid_Turbo
Originally Posted By: PT1
My experience has led me to believe that the most important factor in long engine life is the following:

1. draining factory fill at 1/2 the manufacturers OCI to remove breakin debris and unwanted assembly materials (exception:Honda)
2. following OEM oil viscosity recommendation and OCI
3. replacing air filter often and cleaning PCV often
4. Luck of the draw on assembly day at the factory where your engine was assembled
5. I base this theory on watching multiple friends who have absolutely NO mechanical ability log 300,000+ miles on engines that had nothing but WalMart ST dino oil & filter & air filter changes every 3-4000 miles.
6. I have also had 2 GM and 1 Mazda engines bought new and maintained fanatically begin to fail within 20,000 miles while run on the best synthetic oil.

So, I think it is all just a carp shoot.

What cars do your friends run? What GM and Mazda engine?



The GM engines were a 5.3L and 6.0L and the Mazda was a V6 don't remember what one but all were vary bad piston slappers. ALl started slapping at 10-15k

My friend with the ST oils had a Chevy Blazer V6, 1 Honda accord 4cyl one Honda civic 4cyl and a Nissan Sentra 4cyl. The Blazer EFI went bad at 300k but all the others are still going fine with no consumption.

 

[1sttruck]

" "Then why don't people racing use thinner oils than what they're typically using as it will provide better performance ?"


Because their racing. Are you racing? Am I? Not the last time I checked."

Completely missed the point as it doesn't matter if I or anyone else is racing. The point is that they're using the basic relationship between viscosity / hths and wear to be able to manage acceptable wear limit, just like vehicle manufacturers have. They'd both like to be able to use thinner oils for better performance or better fuel mielage, but can't as wear becomes unacceptable.

No point in going over anything else unless you can understand this one.

 

[Gary Allan]

I don't agree with it. There's a specific output density over an duration of use. As I said, you assert WEAR. I assert LONGEVITY in use. Put an endless sump with qualifying oil ..and you can (probably) run the entire race.



No point in going over anything else unless you can understand this one.

 

[OVERKILL]

The new ZL1 'vette specs 5w30. But it has a HUGE sump............

 

[1sttruck]

"I don't agree with it. There's a specific output density over an duration of use. As I said, you assert WEAR. I assert LONGEVITY in use. Put an endless sump with qualifying oil ..and you can (probably) run the entire race."

The many, many studies supporting the very basic, well understood relationship between viscosity / hths and wear use, fresh oil, used oil, or both, and there is no magic antiwear properties associated with fresh oil. One cannot use 10 weight HDEO in a total loss system and expect similar levels of wear compared to the use of 40 weight HDEO. No study that I am aware of supports the idea that viscosity doesn't matter as long as the oil is fresh. In fact there are conflicting studies on whether used oil results in less wear than fresh oil, with more studies supporting used oil having lower wear.

 

[Gary Allan]

Again, you're swapping horses here. You can't tell me what condition the non-changed oil is in a NASCAR engine at the end of 500 miles. One would be hard pressed to even TRY to pretend that it hasn't decayed on a curve.

Don't you agree? Hence, since this is plain pathetic simpleton logic, one would be hard pressed to argue that there would be SOME REFRESH RATE that would be 100% sustainable over the 500 mile duration that would provide 100% reliability in terms of the lubricants viscosity ..that would be MUCH LESS than its starting viscosity.


In terms of your coveted diesels. The lubricant component is the easiest thing to manipulate. It's the same with stationary power plants and marine applications. Applications where some assumed 100% sensible output is expected. They aren't made to run at 20-30% power output. That is, the sensible reason for their existence isn't to loaf along. They have a near 100% twa at sustained high output.

While you may use your Cummins as a passenger car, anyone who runs empty in a big rig is losing money.

You need a 40 weight for when your oil temps hit 250+ ..where it isn't a 40 weight anymore. Are you destroying your engine?


It's all about margins. You keep insisting that everything be viewed from margins that are routine in one environment ..and rare in almost any other.

The view is way too static and isn't nearly qualified enough for discounting aspects.

 

[1sttruck]

"Again, you're swapping horses here. You can't tell me what condition the non-changed oil is in a NASCAR engine at the end of 500 miles. One would be hard pressed to even TRY to pretend that it hasn't decayed on a curve. "

Let's start simple. Before the start of the race a specific type of oil of a given viscosity / hths is put into the engine. They don't use a much thicker oil for performance reasons. The simple question now is; 'why don't use a thinner oil for better performance' ?

 

[Gary Allan]

Okay, if I'm reading you correctly. If a sheet of copy paper is too thin, I should go out and splice 8"X8" together ..since "thicker is better when an arbitrary thin is too thin"?

That about it?

Margins. If you never hit them (for long) ..is there any gain to thicker oil?? That's simple enough.

That is, in any environment there will be a lower acceptable limit to viscosity. What you seem to attempt to imply, with only using extreme duty as some standard, is that currently offered thin oils cause higher wear. There's just no material justification for the notion. You assume (you truly don't ..but appear to imply) that THAT thin is TOO thin.

 

[1sttruck]

"That is, in any environment there will be a lower acceptable limit to viscosity. What you seem to attempt to imply, with only using extreme duty as some standard, is that currently offered thin oils cause higher wear."

I provided different examples, including current passenger vehicles in the US as well as in Europe, if you disagree please reread previous posts in this thread. What you seem to have been unable to acknowledge is the well understood and accepted relationship between viscosity / hths and wear. I've said numerous times that the vast majority of people will do fine using oils recommended by makers for their market, but that does not mean that the viscosity / wear relationship doesn't exist.

 

[Gary Allan]

Quote:
but that does not mean that the viscosity / wear relationship doesn't exist.


I never denied that it did. I merely assert that it is not existent at ALL TIMES. Just like you're not grenading your diesel w/250+ oil temps where they are not "heavier oils" ..at that time.

Push your oil to 302 while I'm cruising by with 0w-10 @ 212 ..and you're in WAY worse shape than I am. You're surely grinding something up ..somewhere ..but I'll be running pathetically thin oil and be 100% protected from accelerated wear.

See how easy that is??

Q: Is 1sttruck destroying his engine when he's using 15w-40 and hitting 265F+ oil temps on some grades?


Q: If not, and he never hits 225F (IF being the operative word there), would he need a 15w-40 ...EVER?

 

[FZ1]

Thin is in! Europe is running 40% + diesels in passenger cars,hence the tendency toward Hi Vis.

 

[1sttruck]

Car makers in Europe can probably figure out what type of oil to use in different types of engines, viscosity included. With the wider range of operating condtions and typically longer oil change intervals they recognized that the plebian US specs weren't going to cut it so they've relied on their own. As mentioned a number of times when my wife was visiting her friend in Grmany they were often doing 120 mph on the freeway; no crazed speed fiends, just a couple of middle aged housewives driving around. In Spain while tapped out at 125 mph on a 750cc bike I needed to move over for the faster traffic. Getting wild and carzy in the US means putting using half and half in the milk toast instead of nonfat.

 

[Gary Allan]

So if we want to feel "continental" ..we need to use heavier oils?

 

[tdi-rick]

Originally Posted By: 1sttruck
"Viscosity does offer more protection ...from states that 99.99% of those rolling on the road will never see 99.99% of the time"

Then why don't people racing use thinner oils than what they're typically using as it will provide better performance ?


Umm, they do.......
Probably not a good example