5w 20 Facts or Fiction?

[Hirev]

I figured this would be interesting to see what BOBISTHEOILGUY people had to say about these statements from a synthetic oil web site. 5w 20 Facts or Fiction? "You get about 1% better fuel economy, but you get 30% shorter engine life !" "The above statement is based on real life experience and is comparison to SAE 5W-30 Motor Oil." "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."

 

[Jeepster_nut]

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Originally posted by Hirev: I figured this would be interesting to see what BOBISTHEOILGUY people had to say about these statements from a synthetic oil web site. 5w 20 Facts or Fiction? "You get about 1% better fuel economy, but you get 30% shorter engine life !" "The above statement is based on real life experience and is comparison to SAE 5W-30 Motor Oil." "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."

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[sxg6]

: What web site said this? Everything about 5w-20 has already been discussed before. Haven't you seen the other threads on 5w-20 which discuss the topics you've raised?

 

[Rickey]

Oh why not , I couldn't resist Thinner oil at operating temperature equals less film strength in general... right? (HTHS) This means a thinner film of oil to keep the lubricated parts from touching...right? So if the film strength of a 30wt oil gives a protective layer 15 microns thick and a 10 micron particle of debris comes through that bearings oil supply the particle should clear the bearing with no damage... Right? Now drain out that BAAAD old thirty weight, put in some nice new 20wt. Less film strength, thinner film in the bearing journal...oh lets say only 10 microns. Along comes a 10 micron particle... Oh Boy is that particle going to get mangled ouch! So the logical conclusion is that 20wt oil is murder on any poor particles of dirt or whatever might be circulating with your oil at the moment. Beat those particles into submission... use 20wt Now lets go bury that horse before he quits stinking.

 

[Gary Allan]

Well, although based on a real story, this is fiction Everyone knows that this is a jobs program masked as a fuel economy program. If we can destroy cars at a faster rate ..more jobs for the big three ..err..small 5

 

[G-MAN]

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Thinner oil at operating temperature equals less film strength in general... right? (HTHS)

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First off, "film strength in general" and HTHS are two different things. So the answer to your question is "no."

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This means a thinner film of oil to keep the lubricated parts from touching...right?

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Wrong. There is a lot more at play in keeping bearing surfaces apart during hydrodynamic lubrication than just the viscosity of the oil.

 

[SirEager]

Hirve, I don't know where your getting your numbers, but they stink. There so much disinformation about 20 weight oil, we don't need one more person spreading it. First of your 30% more wear number stinks. First of off if you had that much extra wear, you would have extra fiction! MPG improvements are hard to find when you extra friction!!! More likely 5-20 flows better. 5-20 can better find it way around the small passages to better lubricate all the engine parts. Any difference in wear is little to none. I'm starting to under stand that few understand the difference between oil weight, viscosity, and film strength. The writings of AE Haas would be a good place to start.

 

[Rickey]

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Originally posted by G-Man II:

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Thinner oil at operating temperature equals less film strength in general... right? (HTHS)

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First off, "film strength in general" and HTHS are two different things." So the answer to your question is "no." So you are saying that less film strength and/or HTHS is better??? And aren't both of them (HTHS,Film Srength) intimately related? Generaly if not absolutely doesn't more film strength = more HTHS with all other properties the same?

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This means a thinner film of oil to keep the lubricated parts from touching...right?

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Wrong. There is a lot more at play in keeping bearing surfaces apart during hydrodynamic lubrication than just the viscosity of the oil.

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Yea sure there are the other constituents in a properly formulated oil that serve to prevent metal to metal. I understand that! BUT isn't one of the primary functions of the base oil to keep thengs separated. Or did I miss something?

 

[Ray H]

30% is absurd. (Even an idiot knows it's just a hair over 29.99999999999999999%.)

 

[ewetho]

Lets see Oil Analysis proves time and time again that wear is very low with 5W-20 so why worry. Yes there are cars that can not use 5W-20 say a 4.0L V-6 engined Ford. There is a defference at an engineering level. If the car has been OK'd for 5W-20 by the manufacturer then it is probably fine. Any questions run 3000 miles on your current 5W-30 and then 3000 on 5W-20 see what you get on UOA. If wear is minimal on both then no biggie, right. I had a car in the other day, with 189.000 miles on 5W-20 that drove better than most cars I have seen at 60-90K and it was a 4 Cylinder. 5W-20 in an acceptable engine is just fine.

 

[bruce381]

"You get about 1% better fuel economy, but you get 30% shorter engine life !" "The above statement is based on real life experience and is comparison to SAE 5W-30 Motor Oil." Above quote is I think from synlube web site nuff said bruce

 

[bruce381]

"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?" There is a basic formula that you can plug in bearing cleraence, shaft speed and vicosity to get correct oil vis at the operating temp. Hydrodynamic wedge formation vary more in the shaft speed it forms, than how "thick" it is. Since the shaft will kinda center it self "thickness" is the same with thick or thin oils the wedge just starts forming at different shaft speeds with different oil vis. Forgot calculation but in general a THICKER oil will result in faster oil wedge formation and at a much lower speed. But thicker will also result in more bearing drag and takes more HP to pump around engine so yes a thicker oil is better at wedge formation than thin BUT has drawbacks one being bearing starvation as oil is pumped up. bruce

 

[Hirev]

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Originally posted by bruce381: "You get about 1% better fuel economy, but you get 30% shorter engine life !" "The above statement is based on real life experience and is comparison to SAE 5W-30 Motor Oil." Above quote is I think from synlube web site nuff said bruce

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bruce381 You never cease to amaze me and you are correct again. All the quotes are from them. Got to admit you would be the last person I would have thought would be reading the synlube web site.

 

[Rickey]

Hirev: Bruce is trying to pick up some of their secrets...not

 

[bruce381]

read site once for comedy relief. bruce

 

[Hirev]

The part that got me was Ford designed cars to have 10 year or 150,000 miles life. I remember many years ago when ford was bragging about this in a auto magazine. I was not aware they had changed their policy regarding engine life "beyond 100,000 miles" does anyone know if this is true? If it is true wonder why would it change? And when did it change?

 

[Gary Allan]

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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+.

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and on yesterdays engines ........millions of them.....did they grenade? No. Did the 20 weight equivalency change when Group II and Group II+ came around? Is the "new" 20 weight different in CST then the old 20 weight designation. Are the Brookfield brothers rolling over in their graves?? First item tossed out the window.

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Maybe that was why 40wt was so popular then?

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Only in the uninformed DIY crowd. No dealer servicing anything but a light duty diesel used anything other then the current spec'd oil ..which has been (typically for domestics) a 5w-30 ...for about 20 years. So, we can toss that out the window too.

 

[Rickey]

"read site once for comedy relief. bruce" Allready did. One of the most dangerious forms of misinformation is to mix some readily appearant truths in with some not so readily appearant (to some) falsehoods.

 

[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.

 

[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.