Interesting Article on High Vs Low Viscosity Oil..

[JOD]

Originally Posted By: Merkava_4
From the article:
Quote:
If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture.


Did you guys see that?


Well, when you consider that the cars most prone to damage from overheating are cars that also spec A3 rated oils, I don't really think that a thicker oil is going to help. It's like putting a band-aide on a volcano. It seems that a better strategy is to design cooling systems that don't fail, and other failsafe measures in the rare instances when they do.

I don't here of a lot of Ford or Honda products having catastrophic engine failure due to overheating, even with their 'water thin' 5W20 specs; the same can't be said for some other brands that spec very heavy oils....

 

[kschachn]

Like one manufacturer which I won't mention, except to say that if you arrange the letters "B", "M" and "W" in the right order you can guess.

Originally Posted By: JOD
I don't hear of a lot of Ford or Honda products having catastrophic engine failure due to overheating, even with their 'water thin' 5W20 specs; the same can't be said for some other brands that spec very heavy oils....

 

[stchman]

Regardless of what people feel about CAFE, there is little to no reason to use an oil that is not recommended for your vehicle's engine.

The auto manufacturer designs the engine to use a certain viscosity oil. Since the automaker is the holder of the warranty, they get to specify what goes into the engine. If you deviate from that the automaker *might* give you a really hard time in honoring the warranty.

People that say "I'll sue" don't realize the uphill battle they would have trying to sue the automaker. They have far more money and lawyers than you or I have. Do what the manufacturer tells you to and your engine will far outlast the body of the car.

 

[fdcg27]

Originally Posted By: Analyzer
http://www.machinerylubrication.com/Read/518/motor-oils

Here's an thought provoking passage in the article considering 5W20 weight oil:

"To determine if SAE 5W-20 oils provide the same level of protection as SAE 5w30 oils, Dagenham Motors in England, one of the largest Ford dealers in Europe, was consulted. SAE 5w30 is required for warranty purposes in England, and SAE 5W-20 is not even available. If SAE 5W-20 were better for both fuel economy and wear, why would Ford not recommend it for its same engines in Europe?"

Interesting fact considering Europe has notoriously cooler ambient temperatures and more stringent quality controls over oil manufacturers and testing procedures.



So the dead horse is again dragged out for yet another caning?

 

[Garak]

Originally Posted By: demarpaint
Interesting thoughts, following that logic people considering extending their OCI beyond the mfg recommendations might be better served with 5W30 then. Assuming there is no warranty to contend with.

Exactly. And that's why we see A5/B5 and other ACEA specifications (or their derivatives) with European vehicles (or other markets). Falcon's GM SUV in Kuwait called for ACEA specifications and had very long OCIs when following the OLM.

 

[CATERHAM]

Originally Posted By: JOD
Originally Posted By: Merkava_4
From the article:
Quote:
If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture.


Did you guys see that?


Well, when you consider that the cars most prone to damage from overheating are cars that also spec A3 rated oils, I don't really think that a thicker oil is going to help. It's like putting a band-aide on a volcano. It seems that a better strategy is to design cooling systems that don't fail, and other failsafe measures in the rare instances when they do.

I don't here of a lot of Ford or Honda products having catastrophic engine failure due to overheating, even with their 'water thin' 5W20 specs; the same can't be said for some other brands that spec very heavy oils....

With the electronic management safety controls prevalent today, engine damage resulting from overheating is not an issue. If things get too hot the engine will simply go into limp mode immediately; i.e., a rad' hose bursts or the coolant level is too low, etc. As a result an excessively large viscosity reserve is not as necessary as it might have been in the past.

 

[Errtt]

Book on one of my vehicles says 5w-20 for better fuel economy, and 5w30/10w-30 can be used for high temps.
So not knowing what to do, I did 5w-20, then switched to 5w30 when triple digit temps would be fairly normal for a few months, now I'm back to 5w-20 since the cool season is here.
So I'm using both, one or the other, not mixing 5w-20 & 5w30 50/50.
Being a GDI engine, under warranty, I'm also limited to 7.5k OCI normal service. So no long term and hope to keep any dilution in check. Not noticing a hit in mpg, I'm thinking of just sticking to 5w30 (once my stash of 5w-20 is used up).

 

[gfh77665]

Originally Posted By: stchman
Regardless of what people feel about CAFE, there is little to no reason to use an oil that is not recommended for your vehicle's engine.


So, as owners we should ask ourselves: What viscosity is REALLY recommended for my engine? Is it the visc in your owners manual?

Or is it the viscosity listed for the exact same vehicle everywhere else around the globe EXCEPT the CAFE burdened US?

 

[Garak]

Originally Posted By: gfh77665
Or is it the viscosity listed for the exact same vehicle everywhere else around the globe EXCEPT the CAFE burdened US?

Or, more to the point, is it really a bright idea to run 20w-50 or a monograde in a new engine just because it's allowed somewhere else in the world?

 

[gfh77665]

No, "allowed" was never the question, "recommended worldwide" is the point. Its likely not 5-20, 0-20, or 0-16.

 

[Shannow]

Originally Posted By: Garak
Originally Posted By: gfh77665
Or is it the viscosity listed for the exact same vehicle everywhere else around the globe EXCEPT the CAFE burdened US?

Or, more to the point, is it really a bright idea to run 20w-50 or a monograde in a new engine just because it's allowed somewhere else in the world?


As the strawmen are out...if Ford tested their engines and oils for a bajillion miles, Porsche backspecced to 5W-40 some time ago, and a Ferrarri speccing 5W-40 can make it down the driveway without leaving a pile of failed engines in it's wake on a 20 (which I'm informed on the board is really a 30)...that TGMO will keep a Banks Sidewinder in peak condition.

 

[blackman777]

Originally Posted By: gfh77665
So, as owners we should ask ourselves: What viscosity is REALLY recommended for my engine? Is it the visc in your owners manual? Or is it the viscosity listed for the exact same vehicle everywhere else around the globe EXCEPT the CAFE burdened US?

My manual says 0w-20 but I can use 0w30 if the thin oil is not available.

 

[gfh77665]

Good example. I don't know what you drive but I bet your same car around the globe would recommend the 30.

 

[kschachn]

Well yeah, but he's not "around the globe", he's in the US.

My BMW tire pressure placard lists different pressures for the US as compared to the rest of the world. Quite a bit different too. Why is that? Should I use the outside-the-US pressures because they are better?

Originally Posted By: gfh77665
Good example. I don't know what you drive but I bet your same car around the globe would recommend the 30.

 

[KCJeep]

Originally Posted By: Errtt
Book on one of my vehicles says 5w-20 for better fuel economy, and 5w30/10w-30 can be used for high temps.
So not knowing what to do, I did 5w-20, then switched to 5w30 when triple digit temps would be fairly normal for a few months, now I'm back to 5w-20 since the cool season is here.
So I'm using both, one or the other, not mixing 5w-20 & 5w30 50/50.
Being a GDI engine, under warranty, I'm also limited to 7.5k OCI normal service. So no long term and hope to keep any dilution in check. Not noticing a hit in mpg, I'm thinking of just sticking to 5w30 (once my stash of 5w-20 is used up).


Sounds like you're talking about a Hyundia/KIA vehicle. I'm in the same mindset as you, and our 2012 KIA will be getting 5w30 once the 5w20 is used up. The first UOA I did the oil held up very well but the wear wasn't stellar, I'm betting it woulda been better on a 5w30. I will eventually find out. I have nothing to lose but 1/8th of a mpg.

 

[gfh77665]

Originally Posted By: kschachn
Well yeah, but he's not "around the globe", he's in the US.

My BMW tire pressure placard lists different pressures for the US as compared to the rest of the world. Quite a bit different too. Why is that? Should I use the outside-the-US pressures because they are better?

Originally Posted By: gfh77665
Good example. I don't know what you drive but I bet your same car around the globe would recommend the 30.


Well yeah, does the engine know where its at??? Honda is a good example. 5-30 all around the globe, EXCEPT CAFE-US.

So, with this in mind, what is the REAL spec for the Hondas? Can't you see its only CAFE that forced a change for US vehicles? Can you understand that?

Originally Posted By: kschachn
My BMW tire pressure placard lists different pressures.Should I use the outside-the-US pressures because they are better?


I don't care if you run them flat.

 

[OVERKILL]

Originally Posted By: kschachn
Well yeah, but he's not "around the globe", he's in the US.

My BMW tire pressure placard lists different pressures for the US as compared to the rest of the world. Quite a bit different too. Why is that? Should I use the outside-the-US pressures because they are better?


Probably.

I run the 4-passenger pressure because that's all I typically have in my car at the most. Usually it is just me. And the ride quality is a lot better with the lower pressure.

 

[Garak]

Originally Posted By: gfh77665
No, "allowed" was never the question, "recommended worldwide" is the point. Its likely not 5-20, 0-20, or 0-16.

If you're looking globally, you do have to note that several manufacturers do not require a specific grade in other parts of the world. Charts do exist elsewhere; the Europeans, of course, use their proprietary specifications everywhere.

Originally Posted By: Shannow
As the strawmen are out...if Ford tested their engines and oils for a bajillion miles, Porsche backspecced to 5W-40 some time ago, and a Ferrarri speccing 5W-40 can make it down the driveway without leaving a pile of failed engines in it's wake on a 20 (which I'm informed on the board is really a 30)...that TGMO will keep a Banks Sidewinder in peak condition.

You have me all wrong, Shannow. I'm not stating that only 0w-20 must be used worldwide because Brand X says so in North America. I'm merely stating that simply because something is allowed doesn't make it a good idea. I have no issue with the idea of using something of a reasonable viscosity, even if it isn't explicitly called for; and I don't "like" certain viscosities just because they're allowed.

My old Audi allowed for 5w-20 in the winter. It also allowed SAE 40 and 20w-50. I didn't touch any of those three grades. That doesn't mean I was afraid of 15w40 or 5w30 where applicable. I also don't like the idea of using 0w-20 in a new Nissan for a 3750 mile OCI in North America. I'd go with the also-allowed 5w30. Besides, you know I'm not afraid to venture off the reservation, within reason. Look at what's in my G. And we all know you are the Caterham of the Southern Hemisphere.

@gfh77665: Honda may recommend other grades elsewhere, but is the factory fill worldwide this very light 0w-20?

 

[jake88]

I think in all this volleying over the semantics about recommendations between one part of the world and another we are all missing the much larger picture that there is really not that big of a difference. If that marginal difference in viscosity was enough to make any catastrophic differences in engine life then OEMs would have found another way to make their CAFEs. In fact, cutting the viscosity recommendations from xW-30 to xW-20 worked so well that we are talking about xW-16 now.

Viscosity is important. It is the most important single factor for a lubricant. But an engine operates in so many different lubrication regimes from the bearings to the vavletrain to the piston-liner interface that the film is expected to be inadequate in parts of your engine - that is why engine oil has AW additives.

And especially for PCMOs where short trips are commonplace... I would think that thinner oil with faster time-to-lubricate would be better for long-term engine life.

 

[jrustles]

Imagine that. Fuel economy and emission concerns are spreading worldwide. Never saw that coming.

Then again, maybe it's the global cold start protection mandate that's really driving all of this.

PS - I bet that's why BMW has two different tire pressures also - any little bit to help meet published market specs