Engine Design Features That Permit 5w20

[CT8]

Originally Posted By: turtlevette
Originally Posted By: MolaKule


Keeping the water temperature from spiking moderates oil temperature, keeping the oil film from thinning.


I'm going to disagree with that. There is not a hard correlation between water and oil temps. The water temp is based on heat sinking from the block. The oil temp is based on heat sinking oil from bearings, rings, and the bottom of the piston which rivals the hottest temperature anywhere in the engine.

I witnessed my 455 olds jet boat running 300deg oil temps at 6000 rpm when the block was dead cold to the touch. I simply turned up the cooling water from the jet till the block was ice cold thinking that would keep the oil cool. It didn't.



The radiator was too big !!!

 

[CT8]

Originally Posted By: Panzerman
The Best answer I heard was these engines will run on a multitude of oils. I just can not wrap my brain around the use of thinner oils such as 5w20 has any advantage but fuel mileage. Too many people, some how think American engineers have some secret super idea of knowledge and if they told you to spit in the oil filter before installing it, 80% of people would do it because they told you to in the manual, 10% would be too lazy and 10% would say that's as rediculas as using 5w20 for added benefits of lubrication. They would and claim the increased hydrogen in your saliva cleans the valves. If you want better wear and longer life, go with a thicker oil. I have found in "Real Life" of using 5w20 v.s 10w30, the fuel mileage wasnt anything significant.
It is not significant for one car but for millions of cars ,,it adds up. CAFE is why there is Xw-20 these days,The Ford engineers who visited the auto classes I took for continuing education classes in the late 1990s. Better machining and finishing. Anti knock, spark control and precise fuel control allows life with Xw-20. Where I live a Xw-30 is good enough for me.

 

[Shannow]

My L67 oil temperature exceeds the water temp after 15 minutes on the highway.

105-110C is usual (type K thermocouple down the dispstick immediately after shut-off), and holding it in "2" for 10 mins (4,000RPM on highway), it will get to 135C...all well above coolant temperature.

 

[Silk]

Originally Posted By: JHZR2

Further, we love to blame CAFE, but if in the rest of the world the consumer bares more of the injury of low efficiency and lower MPGs, then the vendors may not necessarily care and stay with a status quo.


The rest of the world generally uses smaller vehicles and smaller engines, they already have lower mpg.

 

[Y_K]

Just throw in Climate Change and Gun Control into the discussion and we are set.. Or shall we expand on road profiles for a few more years before doing that?

 

[ledslinger]

I wonder if oil pump design assist utilizing lower viscosity lubricants. Newer pumps have gone away from simple gear type which might cause more shear than new pumps. Newer pump designs could work more efficiently with thinner oils.

Not that there is any direct correlation with the advent of 5W20 oils and to redesigned pumps. Especially since I've never heard any design changes or features introduced on engines when 5W20 was first used. I haven't read what kind of tests exclude some engines from being back specced to 5W20 either.

Since no design features have been identified concurrent with the change to 5W20, implied is an advancement in lubricant technology or a philosophy. The philosophy could be as simple as "for the CAFE benefit, we'll sacrifice minimal engine longevity"

 

[KrisZ]

The thing that a lot of people seem to forget or omit in their posts is that 20 weight oils are nothing new and there was a time, not too long ago to boot, that every manufacturer recommended a range of oil weights depending on the ambient temperature.
This changed when CAFE requirements for posting the official fuel economy numbers included the oil weight. This requires the manufacturer to only state the oil weight that was used to get the EPA gas mileage test as the only "recommended" oil weight for normal use.

Now, because of that, the engine design had to accommodate this new, one oil grade requirement, as they could no longer recommend multiple oil weights, but IMO, CAFE had and still has a major role in forcing the industry to use thin oils.

 

[Quattro Pete]

Originally Posted By: Panzerman
Interesting discussion and explanation of curves and such. Can you now explain why the same engines in other countries without the Café Standards spec the same engines with thicker oil?

Are the OCIs the same in those other countries? For example, the same engines in Europe can be on a much longer variable OCI (20-30k km), and this necessitates more buffer, so you start with 5w-30, and even if it thins out to a 5w-20 during this long OCI, you're still safe.

 

[hattaresguy]

Why is using less fuel a bad thing? Most third world countries don't care about the environment so I would not want to emulate them by running 15w40 in a Coyote just because that's what they do.

Modern engines outlast the cars they are installed in without any issues, so why not try to use less fuel.

If you look at old owners manuals recommending a 20wt oil was not uncommon.

 

[hattaresguy]

Originally Posted By: Quattro Pete
Originally Posted By: Panzerman
Interesting discussion and explanation of curves and such. Can you now explain why the same engines in other countries without the Café Standards spec the same engines with thicker oil?

Are the OCIs the same in those other countries? For example, the same engines in Europe can be on a much longer variable OCI (20-30k km), and this necessitates more buffer, so you start with 5w-30, and even if it thins out to a 5w-20 during this long OCI, you're still safe.


Good point, European owners are used to much longer OCI's.

 

[turtlevette]

Originally Posted By: ledslinger
The philosophy could be as simple as "for the CAFE benefit, we'll sacrifice minimal engine longevity"


That gets thrown out there by many here like it's fact.

I don't believe it's been studied and proven. We don't even have any testimonials to that. Not one that I've seen. Lots of people with high mileage Fords around.

 

[Silverado12]

I wouldn't say oil intervals are much longer in other countries. If you go by the oil life monitor, there have been people posting here that have gone over 10K miles. That's about the same as European countries.

 

[Shannow]

Originally Posted By: turtlevette
Originally Posted By: ledslinger
The philosophy could be as simple as "for the CAFE benefit, we'll sacrifice minimal engine longevity"


That gets thrown out there by many here like it's fact.

I don't believe it's been studied and proven. We don't even have any testimonials to that. Not one that I've seen. Lots of people with high mileage Fords around.


Honda have said that the drive for thinner oils is for CAFE (or CO2 in their home markey), while still providing "adequate" life.

GF6 they have changed the test engines to better reflect the fact that engines are operating more in boundary lubrication these days, meaning that they are operating in the low friction point on the Stribeck curve, which means a reliance on additives rather than hydrodynamic oil films at these points...that's contact, and wear where hydrodynamics has no contact, no wear.

 

[Shannow]

Originally Posted By: Y_K
Just throw in Climate Change and Gun Control into the discussion and we are set.. Or shall we expand on road profiles for a few more years before doing that?


http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/2663633/Re:_CAFE_has_Little_to_do_with#Post2663633

Troll like behaviour when you've nothing to say ?

 

[Evanson]

Originally Posted By: hattaresguy
Most third world countries don't care about the environment


There is no comparison between the *amount* of damage first world countries have done to the environment compared to third world countries.

Caring is meaningless if the results show something otherwise.

 

[Cujet]

Back to the original question, I'll answer it directly.

The major change is directly related to reciprocating mass. Inertia places the highest loads on rod bearings. High RPM increases inertia.

In particular, pistons are far lighter than in the past.

Stock Chevy 350 cast piston

Big block Ford stock and aftermarket

S2000 stock piston and rod. Notice that the piston pin boss is not as wide as the bore? Keeps the pin short and light. Also the very light weight rod.

And, of course, this taken to extremes (Yamaha YZ450 piston)

 

[ledslinger]

Originally Posted By: turtlevette
Originally Posted By: ledslinger
The philosophy could be as simple as "for the CAFE benefit, we'll sacrifice minimal engine longevity"


That gets thrown out there by many here like it's fact.

I don't believe it's been studied and proven. We don't even have any testimonials to that. Not one that I've seen. Lots of people with high mileage Fords around.



You pay for the test and we'll settle it once and for all.

I've never seen a test that confirms if engines will last longer with 5W20 vs 5W30. Anecdotal evidence of engines having long service lives on 5W20 says nothing about how long they would have lasted on 5W30. I am pretty convinced they will last long enough on 5W20, don't know if they'd last even longer on 5W30.

Something I'm pretty sure of is that going to 5W20 for engines that previously ran 5W20 was a bit of a gamble. Somebody did limited testing and stuck their neck out. There are many things in auto engineering that are safer bets and more thoroughly tested than this move was. Conjecture for sure on my part.

 

[friendly_jacek]

Originally Posted By: Shannow
Originally Posted By: edwardh1
Originally Posted By: MolaKule
I would add that in addition to improved parts finishing, part of it is found in the coatings (Titanium and Diamond Like Coatings or DLC), tighter temperature control, and more accurate fuel delivery and timing.


how would tighter temperature control be achieved, or how is it being achieved?


Ford in Oz advertised a system in the Falcon that would respond to a failed cooling system by limiting power output to a level that would control temperatures to avoid catastrophic failure.

Similar systems in Fords (and others) respond to excessive use of the loud pedal, on xW20 oils to limit the power output to make up for the lubricant's shortcomings.

See JHZR2's great post above, with respect to the Stribeck curve...when temperatures are high, and viscosity low because of it, the only way to move the curve to the safer region, to the right is to limit the loading applied to the bearings.



in addition, oil coolers. toyota's 2GR-FE whent from 5W30 to 0W20 when they installed oil coolers. unfortunately it introduced yet another failure point.

 

[fredfactory]

Originally Posted By: ledslinger
Originally Posted By: turtlevette
Originally Posted By: ledslinger
The philosophy could be as simple as "for the CAFE benefit, we'll sacrifice minimal engine longevity"


That gets thrown out there by many here like it's fact.

I don't believe it's been studied and proven. We don't even have any testimonials to that. Not one that I've seen. Lots of people with high mileage Fords around.


You pay for the test and we'll settle it once and for all.

I've never seen a test that confirms if engines will last longer with 5W20 vs 5W30. Anecdotal evidence of engines having long service lives on 5W20 says nothing about how long they would have lasted on 5W30. I am pretty convinced they will last long enough on 5W20, don't know if they'd last even longer on 5W30.

Something I'm pretty sure of is that going to 5W20 for engines that previously ran 5W20 was a bit of a gamble. Somebody did limited testing and stuck their neck out. There are many things in auto engineering that are safer bets and more thoroughly tested than this move was. Conjecture for sure on my part.


Why pay for a test when so many have been done on 5w-20? You can't get much better results than what Kendall got changin oil on a taxi at 10,000 mile intervals going 100,000 miles before an engine teardown. http://www.lubrifiltros.com/pdf/ingles/Taxi_tested_tough.pdf or a video at https://www.youtube.com/watch?v=aqpQzkeNAvg

 

[Cujet]

Gas turbine engines in the aviation world universally use very thin ester oils. Even in the gearboxes. They "seem" to last forever, certainly much longer than automotive engines. Even our very highly loaded helicopter gearbox uses BP2380 oil, the very same oil as the engines.

Which leads me to believe there are only a few reasons certain automotive engines have higher viscosity oils. Camshaft/follower loads might be one reason, connecting rod bearing load is certainly another reason (highly loaded engines nearly always use higher viscosity) , and a more remote possibly could be piston ring/skirt lubrication.