5w 20 Facts or Fiction?

[Rickey]

Gary Allan : Wow I didn't know you could put THOSE in an engine!!! UOA?

 

[JHZR2]

It amazes me that people cannot grasp the fact that EVERY SINGLE engneerng decision is a tradeoff of one sort or another. Youre making tradeoffs whether using a 10, 20, 30, 40, 50, 60 or 70wt, etc. oil. each 'acceptable' viscosity has its share of good and bad points. In reality, from wht we've seen from UOA, etc., there is minimal at dest difference between a 20 and 40wt oil, in most situations. It has been suggested, and I agree, that 20wt oil is really nothing mure than a certification of oil quality for auto manufacturers purposes. Most folks using bargain basement oils who dont care are going to have a better chance of getting a high quality oil using a certified 5w-20 than an uncertified 5w-30... and the 5w-30 very well might spend a *** portion of its life as a 20wt anyway. JMH

 

[Hirev]

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Originally posted by Rickey: Gary Allan: All I am trying to point out here is that there are some fundamental physical properties regarding viscosity in a bearing and that thinner is not always better. To wit: a thicker oil cushion will always offer better protection from oil bourne debris. Now if you don't believe that just go argue with a stop sign.

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Kind of like this link to article

 

[mikemc]

I get bored with a vehicle after 6-8 years anyway.

 

[Rickey]

JHZR2 "It amazes me that people cannot grasp the fact that EVERY SINGLE engneerng decision is a tradeoff of one sort or another." Agreed. I only take issue with folks who claim 20wt to be superior to 30wt under all circumstances. And I will continue to point out instances to the contrary.

 

[toocrazy2yoo]

I would just refer you to Dr. Haas' articles regarding thinner oils. If it's good enough for HIS beasts, if his arguments are that logical, and his engineers say the better flow, with lower pressures are better, it works for me. The superiority sound like it's in the base oils, and the easier flow. Besides, my humble steed specs the stuff anyway.

 

[Rickey]

Dr. Haas is rich enough that he can afford to have any opinion he desires.

 

[Gary Allan]

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Originally posted by Hirev:

quote:

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Originally posted by Rickey: Gary Allan: All I am trying to point out here is that there are some fundamental physical properties regarding viscosity in a bearing and that thinner is not always better. To wit: a thicker oil cushion will always offer better protection from oil bourne debris. Now if you don't believe that just go argue with a stop sign.

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Kind of like this link to article

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Well, let's take a look at their reasoning here.. Thinner oils have less drag, and therefore less friction and wear. Right? Perhaps in the test engine or engines that experience normal operation. But somewhat thicker oils may offer more protection for more severe operations such as driving through mountains, pulling a boat, dusty conditions, short trips, high rpm, overloading, overheating and overcooling. Couldn't the same be said for 30, 40, or 50 weight oil? That is, if you're pusshing 265F+ oil temps with your 40 weight ..you're at a 20 weight. Are you saying that you're grenading your engine with a 40 weight under those conditions? Funny ..there are lots of towing gas engines that routinely use 30 weight ..and live just fine. How can this be? The only thing the severe duty does is shorten the duration of the oil change. Not, typically, the weight. So any reasonably rational and intuitive mind would reason that there is a very broad span of acceptable viscosities that function well in engines ..and that severity of service doesn't so much dictate viscosity as it does the duration of the OCI. Again, you can pour coal tar (70 weight) if you want to base your selection on that select set of circumstances. Rickey 20 weight isn't superior in all conditions ..but the overlap is surely substantial. ..and while we're at it ..what 30 weight are we talking? 9.3cst or 12.49? So, we can then say that since (potentially) 1 CST seperates a "good" oil and a "CAFE low life greedy car company oil" (they appear to hang aroud 8.5CST) ..that if you don't choose your 30 weight well, you're a pinko sympathizer??

 

[Rickey]

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Originally posted by Gary Allan: well, lets for the moment go with your theory ..call it fact. ..and 3 ft of concrete will resist fire longer then 2 ft, right. But you only need 1/2" drywall for a 2 hour firewall. I'll connect the dots, if necessary.

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Lets talk about your analogy for a minute. Which would you rather have between you and a raging fire sir? 1/2 inch of drywall or three feet of concrete? Connect dots please

 

[Gary Allan]

The fact is that in a raging fire a 2 hour firewall is as good as anyone needs. The house is already burned to the ground by then. fire ...1/2" drywall.......2hrs ......no house... There, see? (btw- the 2 hour rating I pulled out of my arse-it's probably not that long ..then again ..either way the house is history) btw-Rickey ..you're doing an excellent job at trolling. My hat is off to you. You're catching 12lb fish with a 6lb test. Gotta play the line just right to allow you to reel in. Congrats

 

[Rickey]

So you would take the drywall?

 

[Gary Allan]

Yes, if I had to pay for it ..and in our case ..lug it around for no good da.m reason. (visions of being Leon in Blade Runner: "It's a test, Leon ...and in answer to your query ..they're written down for me. It's a test designed to provoke an emotional response. Shall we continue?)

 

[Bryanccfshr]

Rickey. Did you read Bruces's post about formation of the oil wedge and thicknes of the wedge?. The thickness of the wedge is not influenced by viscosity, only the speed of the rotating parts and surface area combined with viscosity can influence the time at wich the wedge is formed. The hydrodynamic wedge is going to fill the spaces between the Two pieces and that does not changewith viscosity. Do you understand the pyhsical limitations? You cannot get a thicker film in a wedgeunless the other side of the bearing is open alowing the roating part to move away from the wedge. That would be a journal bearing without a cap for example. If there is enough oil supplied to the bearing to keep it full then it is protected.

 

[XS650]

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Originally posted by Ray H: 30% is absurd. (Even an idiot knows it's just a hair over 29.99999999999999999%.)

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I knew that

 

[XS650]

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Originally posted by Bryanccfshr: Rickey. Did you read Bruces's post about formation of the oil wedge and thicknes of the wedge?. The thickness of the wedge is not influenced by viscosity, only the speed of the rotating parts and surface area combined with viscosity can influence the time at wich the wedge is formed. The hydrodynamic wedge is going to fill the spaces between the Two pieces and that does not changewith viscosity. Do you understand the pyhsical limitations? You cannot get a thicker film in a wedgeunless the other side of the bearing is open alowing the roating part to move away from the wedge. That would be a journal bearing without a cap for example. If there is enough oil supplied to the bearing to keep it full then it is protected.

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Except that's not correct. There would be no wedge if the journal were centered in the bearing. The journal has to run off center for the wedge to form and viscosity has an effect on how far off center it runs and how thick the film thickness is on the loaded side. Lower viscosity, journal further off center, thinner film. http://www.machinerylubrication.com/article_detail.asp?articleid=779&pagetitle=Journal%20Bearings%20and%20Their%20Lubrication Also, an automotive main bearing needs more oil than just enough to keep it filled, it relies on excess flow to cool the bearing

 

[AEHaas]

The journal is always off center in an automotive application when under load. There is a pressure wave or wedge at one end and yes it is larger for a greater viscosity. Oil at the wedge can also act as a solid under extreme pressure, thick or thin. This itself may cause chunks of bearing material to be released. On the other end of the wedge there may be a vacuum and therefore cavitation. This may cause chunks of bearing material to be released. This is known to be the most damaging to bearings. UOA does not fully account for these larger pieces of metal. It is common in the aircraft industry to take apart filters to get a measure of these larger particles. I have become more interested in particle counts in UOA but I do not know enough now to make a judgement. Yet I am studying this for the moment. Many sports cars with less than a thousand miles have ruined engines because the owners rev them up before letting the oil warm up. The damage is from cavitation. I cringe when at a car show and the owner of a car starts it up then revs the engine so everybody can hear the sound of it. They are killing the engine and it is not even under a load. aehaas

 

[Rickey]

G-Man II,SirEager: Which would you say results in a thicker hydrodynamic film in a given engine bearing scenario at equal operating temperature all other things equal? 8cst? 14cst? 17cst? 10cst? I believe that if anyone does their homework that they will find that most of the efficency gains attributed to 20wt over 30wt are due to less windage losses. And most of these claimed gains are within the realm of scientific uncertainty due to their low numbers. In other words it is easier to prove with certainty a 20 percent something than it is to prove a 2 percent something. I'm not anti 20wt just want to set the facts straight. Thinner is not always better. If you can't accept that as fact then more schooling may be necessary. Maybe some engines will last just as long with 20wt as with 30wt, but it remains to be proven. And a few examples don't "prove" anything ladies and gentlemen. A comparison was made to 30wt shearing down to 20wt after some use. But that comparison was made using yesterdays 30wt GrpI Vs: todays 20wt GrpII+. Maybe that was why 40wt was so popular then? Well shearing is shearing is undesireable. Todays 30wt GrpII+ is much more shear stable. If you want 20wt by all means use it. If you want 30wt... Just don't expect everyone to believe that 20wt is always superior on a technical basis. 30 percent more wear? Well I would like to see the proof of that one too. Flame suit on. Scotty!!! Shields to high!!!! Arm photon torpedoes. [ June 04, 2006, 01:00 PM: Message edited by: Rickey ]

 

[toocrazy2yoo]

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The journal is always off center in an automotive application when under load. There is a pressure wave or wedge at one end and yes it is larger for a greater viscosity. Oil at the wedge can also act as a solid under extreme pressure, thick or thin. This itself may cause chunks of bearing material to be released. On the other end of the wedge there may be a vacuum and therefore cavitation. This may cause chunks of bearing material to be released. This is known to be the most damaging to bearings.

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So, Doc Haas, in this scenario (and I assume the lack of rebuttal thus far indicates no disagreement with the scenario), which vis would minimize the effect of the wedge and the wear it creates? A 5W20, or 5W30? I'm going to assume a scenario where the oil is warmed up, but perhaps it would apply in greater fashion to a cold engine? Also, does this scenario apply to normal street cars of average performance? Interesting white papers you've contributed, btw. Tx for those..

 

[Rickey]

Dr. Haas on the subject of cold wear: Wouldn't cold clearances especially in the piston/ring to bore area also be a large factor in a cold rev abuse scenario? Especially since high performance engines tend to need more generious clearances due to more heat stresses and thermal expansion at WOT? I realize that having dissimilar metalurgies for piston and cylinder aggrevate this condition. And having all aluminum construction (with Nikasil for the piston bore)such as Porsche and others have done goes a long way to solve this. And aluminum bearing bores aggrevate the bearing situation. And I agree with the ideal of a zero viscosity bearing fluid or gas. And 20wt is a step in that direction. There are always tradeoffs. And at what point do the tradeoffs exceed the gain? Well sir I maintain that the answer to that question is a variable one, and depends on a number of conditions outside the control of the oil manufactuer. Therefore the warning not to use 20wt in engines not approved for its use. I dont take issue with you sir. And I do take issue with those that represent 20wt as a panacea,without fault,infallable,and universal. It too has limitations. Some of which are better served by 30wt or even 40wt. Good Day.

 

[Rickey]

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Originally posted by Bryanccfshr: Rickey. Did you read Bruces's post about formation of the oil wedge and thicknes of the wedge?. The thickness of the wedge is not influenced by viscosity, only the speed of the rotating parts and surface area combined with viscosity can influence the time at wich the wedge is formed. The hydrodynamic wedge is going to fill the spaces between the Two pieces and that does not changewith viscosity. Do you understand the pyhsical limitations? You cannot get a thicker film in a wedgeunless the other side of the bearing is open alowing the roating part to move away from the wedge. That would be a journal bearing without a cap for example. If there is enough oil supplied to the bearing to keep it full then it is protected.

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What about side leakage? (Caution hypothetical sarcasm ahead) Oh darn there I need a bigger oil pump and tighter bearings for that 2Cst oil I just put in! But I did increase engine efficency by .05 percent