Optimal kinematic viscosity for mimimal wear?

[SuperBusa]

Originally Posted By: FZ1
Well,boys,if runnin' a thinner oil on start up ain't better,then how come they invented multi-weight oils?????


A 0w-20 or 5w-30 (or any multi-viscosity oil) is still more viscous at cold start-up then when it's hot. Pumpability when cold to provide adequate lubrication ... that's the main reason for multi viscosity oils.

 

[CATERHAM]

Measuring boundary lubrication friction of valve train shims at very low rpm's may be interesting but falls far short of the entire picture of engine wear as a whole.

UOA measures engine wear in its totality.

 

[BuickGN]

Originally Posted By: CATERHAM
Measuring boundary lubrication friction of valve train shims at very low rpm's may be interesting but falls far short of the entire picture of engine wear as a whole.

UOA measures engine wear in its totality.


Not even close. UOA measures wear particles of a certain size. Anything larger goes undetected.

Why do you and Dr Haas and Poke ignore this? They're basically worthless in determining wear.

I've had two engines self destruct with oil that looked like glitter yet still manage to have ok UOAs. Personally I believe my own teardowns over UOAs.

 

[CATERHAM]

Originally Posted By: OVERK1LL
Originally Posted By: Ben99GT
I'm just trying to figure out how a 4400 mile engine with wear metals trending down over 1400 mile OCIs proves anything?

So if he switches back to 10W-60 and UOAs show wear metals fall again does that prove thicker is better?

I was wondering the same thing...... Not to mention using UOA's as the complete basis for this kind of argument is a huge
stretch to begin with.


If Ferrari new that under no circumstances would the sump engine oil temps ever exceed 180F I'd bet they would be specifying a 0W-20 oil and definitely not 10W-60. What a coincidence, that's what Dr. Haas is using!

 

[BuickGN]

Originally Posted By: CATERHAM
Originally Posted By: OVERK1LL
Originally Posted By: Ben99GT
I'm just trying to figure out how a 4400 mile engine with wear metals trending down over 1400 mile OCIs proves anything?

So if he switches back to 10W-60 and UOAs show wear metals fall again does that prove thicker is better?

I was wondering the same thing...... Not to mention using UOA's as the complete basis for this kind of argument is a huge
stretch to begin with.


If Ferrari new that under no circumstances would the sump engine oil temps ever exceed 180F I'd bet they would be specifying a 0W-20 oil and definitely not 10W-60. What a coincidence, that's what Dr. Haas is using!


That's pure speculation on your part unless you're a Ferrari insider.

Again, you sidestep the worthlessness of UOAs in determining wear.

 

[CATERHAM]

Originally Posted By: BuickGN
Originally Posted By: CATERHAM
Measuring boundary lubrication friction of valve train shims at very low rpm's may be interesting but falls far short of the entire picture of engine wear as a whole.

UOA measures engine wear in its totality.


Not even close. UOA measures wear particles of a certain size. Anything larger goes undetected.

Why do you and Dr Haas and Poke ignore this? They're basically worthless in determining wear.

I've had two engines self destruct with oil that looked like glitter yet still manage to have ok UOAs. Personally I believe my own teardowns over UOAs.


We're talking gradual wear, not catastrophic failure.

 

[BuickGN]

Originally Posted By: CATERHAM
Originally Posted By: BuickGN
Originally Posted By: CATERHAM
Measuring boundary lubrication friction of valve train shims at very low rpm's may be interesting but falls far short of the entire picture of engine wear as a whole.

UOA measures engine wear in its totality.


Not even close. UOA measures wear particles of a certain size. Anything larger goes undetected.

Why do you and Dr Haas and Poke ignore this? They're basically worthless in determining wear.

I've had two engines self destruct with oil that looked like glitter yet still manage to have ok UOAs. Personally I believe my own teardowns over UOAs.


We're talking gradual wear, not catastrophic failure.


That doesn't make a difference. Are you saying the UOA only picks up gradual wear?? I didn't break anything, I wore an engine out in the course of 10,000 miles and the UOA showed pretty normal results. It's worthless in determining wear.

 

[CATERHAM]

Originally Posted By: BuickGN
Originally Posted By: FZ1
Some of us just prefer to run a cooler running, better flowing oil. I haven't heard any metal to metal scraping yet in 99,000 miles in my 5-20 filled Honda. Lol. BTW when you pull a guy 3 cars out of the hole,there ain't no need to power shift down the track.


When it's a ZR1 there is. Besides, mine is an auto. It just happened to dead hook at 35mph when I put it to the floor which is rare. This was a random street encounter. We've been eyeballing each other going opposite ways for a couple months now. Finally met up at a light. It's for reasons like this I run it on slicks all the time.


And what oil does GM spec' for the 638 hp ZR1...wait for it....M1 5W-30. Now I'm of to bed; it's after 4am here.

 

[BuickGN]

Originally Posted By: CATERHAM
Originally Posted By: BuickGN
Originally Posted By: FZ1
Some of us just prefer to run a cooler running, better flowing oil. I haven't heard any metal to metal scraping yet in 99,000 miles in my 5-20 filled Honda. Lol. BTW when you pull a guy 3 cars out of the hole,there ain't no need to power shift down the track.


When it's a ZR1 there is. Besides, mine is an auto. It just happened to dead hook at 35mph when I put it to the floor which is rare. This was a random street encounter. We've been eyeballing each other going opposite ways for a couple months now. Finally met up at a light. It's for reasons like this I run it on slicks all the time.


And what oil does GM spec' for the 638 hp ZR1...wait for it....M1 5W-30. Now I'm of to bed; it's after 4am here.


Something thinner than my 720hp (crank hp) V6.

Ignoring the UOA question again?

 

[yannis]

If you google you will come across these statements.

""FORD which has previously designed cars to have 10 year or 150,000 miles life has reduced the mileage life expectation to "beyond 100,000 miles" on vehicles that are operated on SAE 5W-20 Motor Oil.

HONDA only claims "useful life" as 7-years or 70,000 miles in EPA certifications for their CIVIC which uses SAE 5W-20 Motor Oil, while the previous model that utilized SAE 5W-30 Motor Oil was certified for 10 year or 100,000 mile durability.""

 

[yannis]

Originally Posted By: friendly_jacek
Some more tidbits from career tribology scientists. Link: http://findarticles.com/p/articles/mi_qa5322/is_200711/ai_n21298415/?tag=content;col1


Great article, thanks.

 

[johnbottilaw]

If you drive a BMW M series car, then 10w-40 or 20w-50 is a dangerously "thin" oil.

I disagree with this. In the owner's manual for M engines it says 40 and 50 weights are acceptable and not a problem if 60 weight unavailable. I have UOA's from my 2008 M3 using 30 weights that show far less wear than shorter change intervals with the 10w-60.

 

[JAG]

Originally Posted By: BuickGN
Originally Posted By: AEHaas
Dragsters start out with a 70 grade oil but end up with almost straight fuel as oil by the end of the strip. This is why they start out so thick.

Thin oil, a 20 grade is best for all around use:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1543003#Post1543003

aehaas


Uh, which kind of dragsters??? Are we really comparing Top Fuel dragsters to street cars? Fine, my GN is representative of every car, even grandma's Crown Vic, and they all need a 20w-50 to survive. That makes as much sense.

I've worked with mechanics from a Top Fuel team and I can tell you 100% that fuel dilution is not the only reason they use a thick oil.

20wt is the best for all around use?? Are you serious? So you can really make a blanket statement using meaningless UOAs about all cars?? You also don't believe HTHS is important.
This is the kind of nonsense that some unsuspecting person is going to believe because you're a doctor and own a few nice cars. It's unfortunate.

+1. It's very unfortunate. Shame on you AEHaas for posting that ridiculous statement.

 

[Junior]

Originally Posted By: BuickGN


I guess what I'm looking for is an admission that higher power outputs regardless of temperature require higher viscosities to keep things separated.


In general for a given bearing, higher loading or lower RPM will require a higher viscosity. But the viscosity selected has to take into account the actual operational conditions and physical size of the bearing. For example, and F1 engine has a high specific power output per liter but I have read they use low viscosity oils. Of course they spin 19,000 rpm and are not a fair comparison when speaking in terms of passenger car engines.

The point is, viscosity is selected based on the application not just the power output alone.

 

[Sayjac]

Originally Posted By: AEHaas
Thin oil, a 20 grade is best for all around use:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1543003#Post1543003

aehaas

 

[ekpolk]

Originally Posted By: BuickGN
. . .
Not even close. UOA measures wear particles of a certain size. Anything larger goes undetected.

Why do you and Dr Haas and Poke ignore this? They're basically worthless in determining wear.

I don't ignore this at all. I disagree with the sweeping condemnation of UOA, have said so, and I guess that's where we are. To be more precise, I should say that I largely disagree. I agree that if whatever is happening in your engine is producing wear debris that's outside the range of the type of analysis you're using, then it won't see it. On the other hand, it's pretty evident that UOA is effective at detecting and measuring wear material that is within its "range". It's not an all-or-nothing thing. UOA results are effective in detecting wear, so long as they are viewed with a proper understanding of the limits of the test.*

Originally Posted By: BuickGN
I've had two engines self destruct with oil that looked like glitter yet still manage to have ok UOAs. Personally I believe my own teardowns over UOAs.

Perhaps if you had used a lower viscosity oil. . . Couldn't resist that bait.

 

[CATERHAM]

Originally Posted By: johnbottilaw


If you drive a BMW M series car, then 10w-40 or 20w-50 is a dangerously "thin" oil.

I disagree with this. In the owner's manual for M engines it says 40 and 50 weights are acceptable and not a problem if 60 weight unavailable. I have UOA's from my 2008 M3 using 30 weights that show far less wear than shorter change intervals with the 10w-60.


+1

 

[ekpolk]

Originally Posted By: johnbottilaw


If you drive a BMW M series car, then 10w-40 or 20w-50 is a dangerously "thin" oil.

I disagree with this. In the owner's manual for M engines it says 40 and 50 weights are acceptable and not a problem if 60 weight unavailable. I have UOA's from my 2008 M3 using 30 weights that show far less wear than shorter change intervals with the 10w-60.


That fine, I'm no expert on BMWs. I used this example only to highlight the problem is using hazy, subjective terms such as "thick" or "thin". Turning back to the example, what's "thick" to my 0w-20 Camry might be very "thin" for the M-series BMW. I should have made what I was saying clearer.

 

[CATERHAM]

Originally Posted By: ekpolk
Originally Posted By: johnbottilaw


If you drive a BMW M series car, then 10w-40 or 20w-50 is a dangerously "thin" oil.

I disagree with this. In the owner's manual for M engines it says 40 and 50 weights are acceptable and not a problem if 60 weight unavailable. I have UOA's from my 2008 M3 using 30 weights that show far less wear than shorter change intervals with the 10w-60.


That fine, I'm no expert on BMWs. I used this example only to highlight the problem is using hazy, subjective terms such as "thick" or "thin". Turning back to the example, what's "thick" to my 0w-20 Camry might be very "thin" for the M-series BMW. I should have made what I was saying clearer.

It's all about temperature. That's why it's gets very misleading to talk about any SAE grade of oil without that temperature context. If you're talking kinematic viscosity you've largely eliminated the temperature component from the the discussion.
I love to tell my friends I'm using a 0W-20 oil at the track for the shock effect. The reality is I'm running a 9 cSt oil. And on the street typically a 17 cSt oil.

 

[CATERHAM]

Originally Posted By: Junior
Originally Posted By: BuickGN


I guess what I'm looking for is an admission that higher power outputs regardless of temperature require higher viscosities to keep things separated.


In general for a given bearing, higher loading or lower RPM will require a higher viscosity. But the viscosity selected has to take into account the actual operational conditions and physical size of the bearing. For example, and F1 engine has a high specific power output per liter but I have read they use low viscosity oils. Of course they spin 19,000 rpm and are not a fair comparison when speaking in terms of passenger car engines.

The point is, viscosity is selected based on the application not just the power output alone.



+1 F1 engines use 5 wt and 10 wt oils. It was the advances in engine lubrication technology back in the 80's and 90's that led to the rev's peaking at 21,000 and even 22,000 rpm. Unfortunately the technological development has been capped and the rev's are now limited to 18,000 rpm. They still sound sweet though!