Automotive engineers and oil

[Garak]

Originally Posted By: Inspecktor
If there was no CAFE, would we see any 20 wt oil on the market?

20 grades existed before CAFE. They also exist in countries outside the CAFE regime. The ACEA even fits them into A1/B1.

JW_Ford: Variable valve timing systems are not limited to engines that run 20 grades, not by a long shot.

 

[bluesubie]

Originally Posted By: Moondawg
It has been stated several times on BITOG, that a car/truck manufactures engineers know what is the best weight engine oil for a particular engine and that is why they spec that weight in the owners manual. Is this always true? Do the manufactures and engineers really design an engine around one or at most two particular weights of engine oil?

IMO, and as some others have inferred, it depends on where those engineers are located and who/what they are influenced by.

Subaru of America/Subaru Canada recommendations:
BRZ = 0W20
All turbos after 2011-ish = 5W30. Turbos prior to 2011 allowed 5W40.

Subaru Japan
EJ engines currently allow 10W50.
BRZ, all DI turbos, and H6's allow 5W40 and Euro 0W30.

 

[kschachn]

Originally Posted By: CT8
XW-20 is Cafe .


So it is a bad choice for that reason?

You should have told me before I ran it for over 200,000 miles on my old 1MZ-FE and NEARLY 150,000 miles in my ECHO.

 

[Clevy]

There was a time when I drank the cafe kool aid and swore 20 grades were junk and engines that used it were going to dissolve.
That was 15 years ago.
For example the Ford 4.6L 2v. Originally called for a 5w-30 in 1996. In 2000 it got back spec'd to a 20 grade,along with the 5.4l in all the trucks.
I still see that generation Ford truck on the job sites. All beat up hauling tools,hauling garbage,still hauling.
The Mustangs which tend to be driven hard are still kicking too. I've personally seen trucks badly abused with 500000+ on the odo and never had a valve cover off.
Honda and Toyota certainly aren't dissolving either.
So today I've learned that the 20 grade does just fine in engines with tight enough bearing clearances to maintain proper oil pressure.
So yes it was CAFE driven at first however it's absolutely absurd to believe engine life will suffer due to its use. Tens of millions of vehicles running the stuff proves otherwise.
And those who keep spouting the CAFE mantra apparently can't comprehend in the applications it's specified for it does just fine. Yet they still spout it over and over again because they apparently are unable to absorb new information.

 

[userfriendly]

Back in the day you could watch the oil pressure go down as the miles rolled by, then you knew it was time to change the oil. Perhaps it was getting fuel diluted because of the sticky choke or the mouse nest in the air cleaner.
If you let the clutch out too fast the car would jump up and down when the engine was cold, but you could keep it running by pumping the gas pedal.

The original cylinder dropping technology was a fouled spark plug, an ignition wire cooked on the exhaust manifold or one of each.

Just for fun, lets take an old school inline 6, convert the fuel system to lpg, put an 8 speed automatic transmission behind it, 0w20 in the crankcase and see how long it lasts.

 

[BrocLuno]

If the machine work was good enough on the rebuild and the right bearings were chosen, it'd prolly run 300,000 miles just fine

 

[userfriendly]

I ran a rebuilt +.060" SBC with forged pistons for 120,000 miles on lpg. One day I had to take the heads off because of a dropped hard seat. The cross hatch was still perfect right to the top of the cylinder.
My point being, as long as the bearings are happy, and there is no reason they wouldn't be with XW20, I believe the rest of the engine will be fine too.
The absence of fuel dilution and clutch popping are two of the many changes from the past that allow engines to operate on thinner engine oils.

 

[Claud]

Didn't Model T Fords run with a 20 weight oil back in the day?.
Then again I doubt a Model T engine built to original specification would have much of a lifespan compared to anything modern no matter what oil was lubricating it.

Claud.

 

[Shannow]

Originally Posted By: userfriendly
My point being, as long as the bearings are happy, and there is no reason they wouldn't be with XW20, I believe the rest of the engine will be fine too.
The absence of fuel dilution and clutch popping are two of the many changes from the past that allow engines to operate on thinner engine oils.


I agree completely on both points...and would like to add reliability of the cooling system as well.

Back in my carbed V-8 days, temperature control was woeful (worst bore wear I've ever seen was where a guy ditched the thermostat...top ring reversal point was massively worn)

 

[Shannow]

Originally Posted By: Claud
Didn't Model T Fords run with a 20 weight oil back in the day?.
Then again I doubt a Model T engine built to original specification would have much of a lifespan compared to anything modern no matter what oil was lubricating it.

Claud.


the "20s" back in the day had an HTHS that some on this board would state "makes them really a 30"...2.9 is about the same as an ILSAC 30.

 

[fdcg27]

Engines are not designed around any given viscosity grade.
Almost any engine will live a very long life on just about any viscosity grade you might care to use.
There are plenty of engines capable of 250K on a 0W-20 grade oil for which a 5W-40 is recommended in other markets.
Either way, engine life will not be compromised.
You can use thicker or thinner oil in most any engine as you see fit.
The engine isn't going to suffer either way.
Engines aren't nearly as sensitive to viscosity grade as some seem to think.

 

[stchman]

Originally Posted By: hatt
Originally Posted By: stchman


The truth is, if one uses the recommended viscosity and follows the manufacturer's recommendations for a maintenance schedule, the engine will far outlast the body.
Plenty of 20+ year old work trucks running around here. I wonder how many are on the factory engine. The engine outlasting the body may be relevant in the rust belt, but not everywhere with every vehicle.


Then those engines weren't properly cared for. It is not 100% of the time, but it is the norm.

 

[SR5]

Originally Posted By: Shannow
Originally Posted By: userfriendly

The absence of fuel dilution and clutch popping are two of the many changes from the past that allow engines to operate on thinner engine oils.


I agree completely on both points...and would like to add reliability of the cooling system as well.


Three good points. Heavy oils in the old days were to give a bigger margin for error.

I remember driving through the outback in a 70's vintage car, in the middle of summer. The temp. warning light was slightly glowing in the background the whole time. Even with fresh oil, fresh air filter and good coolant.

 

[bbhero]

Ok OK... Hold on. So if I am hearing you all right then the following statement is true.
"Even if a car is specified to run on a 5w30 oil then it would be just fine with a 0w20."

I am not disagreeing with you all at all. I just want to make sure I am correct in my reading of what y'all are saying. If so.. Then this is very interesting. Due to the fact that means a number of quality 0w20s could be run in my car as well. Which is an interesting thought. I know the 2013-16 VQ35 motors are now specd for 0w20 full synthetic. There are likely 0 differences between these VQs and my own.
I always thought there was a balance between oil that was thick enough to protect against wear and not too thin that it would not be able to provide enough protection against wear. I've read on here that the HTHS is really what provides wear protection at operating temp. Not 100°C operating viscosity. So would a oil with a HTHS of say 2.6 be good enough to provide good wear protection?? Just as good as a oil with a HTHS of 3.1 ? Very interesting...

 

[Shannow]

Originally Posted By: bbhero
Ok OK... Hold on. So if I am hearing you all right then the following statement is true.
"Even if a car is spec


Careful, I was replying to userfriendly, whose statement included "as long as the bearings are happy"...that's a critical qualifier.

If there bearings are happy (no way to determine that using techniques here), the pistons/rings, and cams will probably be fine.

 

[bbhero]

Well yeah I understood that

That was a part of my thinking in what I posted there. Though I didn't type it out. My bad for that being absent in my response. Still an interesting thought though.

 

[userfriendly]

When is a XW20 not a XW20? When the engine oil is diluted with fuel, oxidized, overheated, contaminated and in a temporary or permanent shear condition.
What can make the engine bearings unhappy when the correct grade of engine oil is used as per manufactures 'instructions?
My foot slipped off the clutch which lugged the engine on the same day I filled up with low octane gasoline and advanced the timing.
I missed a shift and the engine went to 9,000 rpm.

 

[SR5]

I don't know what the others were saying or are planning to do. But as my cars have improved, I have relaxed my margin for error over the years.

Before I used 20W50, 20W60 mineral oil or 10W60 synthetic. But this was driving Carb'd cars in hot summer conditions.

With modern fuel injection I'm using 10W40 semi-synthetic. But thinking about 5W40, 0W40 or 5W30 full synthetics next. All A3/B4

If this keeps up, I'll soon be wearing tie-dye and beads.

 

[userfriendly]

Krykie!

 

[A_Harman]

Originally Posted By: HerrStig
Originally Posted By: Joe90_guy
Every engineer who joins an OEM wants to design a Ferrari.

However not everyone can design a Ferrari, so some engineers settle for designing other cars.

Not anyone can design a car, so some engineers design engines. Others settle for designing interiors. Other have to settle for designing door handles and exhaust pipes.

The guy that looks after oils in an OEM never had a hope in [censored] of doing any of the above jobs. He can't imagine, he can't draw, he doesn't know one end of a spanner from the other. In fact he was the person that settled for the position of Safety Officer but flunked the job interview.

You think I'm joking? Nope...not a bit of it.
How do you "flunk" a job interview?


I flunked a job interview at Holley carburetor 20 years ago when I told my potential boss that carburetors were old tech, and fuel injection was the future. I was right, but I didn't get the job.