"Cushion" of a more viscous motor oil worth it?

[wemay]

A 5w20 with an HTHS of 3.1 is an exception, not the rule. Most are 2.6 or 2.7.

But yes, your anecdote points to the 5w20 being more shear resistant (barely [.1]) in that specific case.

 

[StevieC]

The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.

 

[RDY4WAR]

Of course a 5w-20 with a HTHS of 3.1 is the exception but just making a point.

What about the additives of both? API/ILSAC limits aside, could higher levels of ZDDP make up for a "thinner" oil spending more time in mixed and boundary lubrication regime?

Example...

HTHS of 3.6 with 800 ppm Zn and P

VS

HTHS of 2.6 with 1200 ppm Zn and P

 

[ZeeOSix]

Originally Posted by RDY4WAR
Ultimately the HTHS determines your cushion and some 30 grades have a higher HTHS than some 40 grades, some 20 grades higher than some 30 grades, etc.


Not very many cases of that going on, but it can happen with specialty oils.

 

[Overfill]

deleted

 

[wemay]

Originally Posted by StevieC
The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.


Yup, just yesterday.

 

[ZeeOSix]

Originally Posted by StevieC
The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.


Under pretty benign (and relatively low oil temperature) conditions I would suspect.

 

[BrocLuno]

Originally Posted by StevieC
Chromium would be indicative of ring wear right? If so mine was 0ppm on my UOA in the Journey with 9K on the 5w20 oil. I should have more than 0ppm if the rings were wearing. I should also have aluminum for the piston and that was also 0 and the iron was 4ppm which is really low for normal wear. This was an engine that was spec'ed for a 30 weight previously as well.

I'm not saying all situations are like this but in this case it was and many engines seem to go a long life with 20 weights. We have had them for over a decade now and now they are moving some engines to 16 weights. I couldn't see OE's doing this if they weren't sure that this oil would give long engine life.



Not necessarily. Chrome is a ring facing often used for rapid seating. But the rings may not be chome all the way through. They are usually plasma chrome coated iron rings. Plain rings are iron all the way through. Of course there are steel rings, chrome steel rings, etc. It all depends on the design and how they're supposed to interface with the iron block ... Mostly it depends on the amount of nickle in the block iron.

 

[wemay]

Originally Posted by ZeeOSix
Originally Posted by StevieC
The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.




Under pretty benign (and relatively low oil temperature) conditions I would suspect.



150c

 

[ka9mnx]

Originally Posted by RDY4WAR
Of course a 5w-20 with a HTHS of 3.1 is the exception but just making a point.

What about the additives of both? API/ILSAC limits aside, could higher levels of ZDDP make up for a "thinner" oil spending more time in mixed and boundary lubrication regime?

Example...

HTHS of 3.6 with 800 ppm Zn and P

VS

HTHS of 2.6 with 1200 ppm Zn and P



Well, yes in that situation. The valve train (and the rings/liners at certain points of the stroke) would benefit with higher Zn because they run in mixed/boundary lube. But, the bearings (and rings/liner at mid-stroke) would suffer more wear with the lower HTTS because they are running in hydrodynamic lube. So if you are looking for the least wear, you need both.

BTW I don't thing there would be much difference in wear in a normal engine between 800 ppm and 1200. You could compare 800.

 

[ZeeOSix]

Originally Posted by wemay
Originally Posted by ZeeOSix
Originally Posted by StevieC
The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.


Under pretty benign (and relatively low oil temperature) conditions I would suspect.

150c


Sure, the HTHS is rated at 150 deg C, but what was the oil temperature during the actual wear testing? The note in the graph says data from a controlled field test, so I doubt the oil was running at 150 deg C in the field.

 

[ka9mnx]

wemay:

This is the question OEM's and oil blenders have been struggling with for a while. And now the SAE with the new J300.

Me? I tend to keep vehicles for a long time so I lean towards cushion but within reason. I tune my vehicles for MPG because that's a hobby. So it's cushion with conservation.

Does that make sense?

 

[demarpaint]

Originally Posted by VeryNoisyPoet
Here's an example of a non-track use that's fairly hard on a daily driver. My car's oil will run 90C to 105C (194F to 221F) during a normal highway cruise, with oil pressure around 45 psi at 2400 rpm. If I'm on a mountain grade at freeway speeds in 3rd gear at 3600 rpm for an extended amount of time with a heavy load on board, oil temps can rise to 127C / 260F. Pressure will drop to 35 psi despite the higher rpm due to decreased viscosity. This is with an oil to coolant heat exchanger.

A thin oil will provide plenty of protection at standard temperatures, but may thin out too much when pushed hard, even if not being thrashed on the track. Won't cause rapid failure, but may accelerate wear if the vehicle is routinely operated under heavier load in hot ambient temperatures.

The other concern with DI and turbocharged engines is fuel dilution thinning the oil further even if temperatures remain sane. A higher initial viscosity oil can tolerate more contamination before its lubrication properties are compromised. In a highly stressed turbocharged engine, thin contaminated oil is the last thing you want when boost comes up.



That's where common sense and a bit of knowledge pays off. Good on you for observing what was going on! In a situation like yours it might pay to get a UOA and see if the oil you're using is up to the task. If need be then bump it a grade.

 

[dave1251]

I will use a 20 grade without hesitation. Being said I will use up to a 40 grade without hesitation either. This is due to the climate I live in. It's not uncommon for me to hop into my truck at 4AM and it's 80F or higher.

 

[StevieC]

Originally Posted by ZeeOSix
Originally Posted by StevieC
The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.


Under pretty benign (and relatively low oil temperature) conditions I would suspect.


You mean typical engine use without Turbo's, without towing, loafing around town? The Journey you could monitor engine oil temperature and it would rarely get above 100 celcius and that was in the summer both in traffic or the highway.

 

[gathermewool]

I've got to re-state the obvious: no BITOG-maintained car will this matter in. If the OM states a lower viscosity than you're typically comfortable with (or that is recommended in other countries...), regardless of the motivation for its recommendation (e.g., CAFE), the likelihood of having an oil-related issue is more dependent on design and manufacturing defects than the chosen oil itself.

If Subarus from a certain vintage are known for oil-burning, a small percentage will be documented and due to owner neglect. The next, higher percentage will likely be due to some sort of manufacturing defect that is fixed due to meeting the consumption criteria. The next, higher percentage will likely be due to some sort of manufacturing defect, but not fixed due to not meeting the criteria for repair (these are the saddest lot of people). The largest percentage of manufactured vehicles, for the vast majority of owners, will experience zero to inconsequential amounts of consumption throughout the life of their vehicles. Furthermore, I'd argue that none of said consumption has to do with the viscosity of oil used (if meeting the OM requirements). Note: Subaru is pretty generic with their oil requirements compared to some manufacturers.

If I was concerned in the least about my FB25, I'd err on the side of caution and use only XW-30. I am more cautious with my FA20DIT and do use a slightly higher viscosity oil, but that's because of its nature. The FA20DIT produces boost very early in the rev range, especially for people who drive it like my wife, in I-mode, where-in boost is used for a certain requested torque over a higher, more aggressive RPM, for most scenarios. Regardless of bearing design, I think an ~11-12cSt oil at temp is prudent, when boost exceeds 10# at 2,500 RPM. The recommended 5W-30 would likely be fine, but XW-40 gives me peace of mind, especially at a Cobb Stage 1 tuned state.

Peace of mind: a hated phrase of mine, but I still succumb to its lure in certain situations. The same holds true for why I'll dump and replace the oil in my OPE yearly, even if it's not needed (I remember NEVER replacing the oil in our family mower growing up, because we didn't know better - ran fine every year! Or so we thought....) Ahhhhh, now that I can afford peace of mind!

 

[Shannow]

Originally Posted by wemay
We've all seen the posts where a member offers genuine advise to the tune of, "i would recommend a heavier viscosity so you have more of a cushion...." As opposed to running what the manufacturer recommends.

How much is a cushion worth? Does it really afford you the ability to transform a vehicle with a machining issue, dilution, design flaws, into a reliable non-oil consuming ride for an appreciably longer period?

Assuming it's under warranty, would you even want to mask what you consider an issue since it may only "prolong the inevitable" (if a design flaw) until after your warranty is over, if that long?

EDIT: not talking about cars you take to the track. Just daily drivers.



Same as the last one...framing a thick/thin thread and setting preconceptions.

Why keep it up ?

 

[Shannow]

Originally Posted by StevieC
Originally Posted by ZeeOSix
Originally Posted by StevieC
The paper posted in the other thread showed no difference in wear between HTHS of over 2.3 to the 3ish mark. So 2.6 would be fine.


Under pretty benign (and relatively low oil temperature) conditions I would suspect.


You mean typical engine use without Turbo's, without towing, loafing around town? The Journey you could monitor engine oil temperature and it would rarely get above 100 celcius and that was in the summer both in traffic or the highway.


IN SOME ENGINES...why do you keep leaving that out SevieC…That's WHAT the paper said

Oh, yeah, I know...

 

[StevieC]

Did they study every engine? NO

Are lots of engines running a 20wt perfectly fine for hundreds of thousands of trouble free miles under these normal circumstances? YES

What did I leave out?

 

[Shannow]

Originally Posted by wemay


150c




See this is why I hate these threads, and trying to bring anything to them.

You people can't even read the charts (that I provided), then use them to "prove" your case.

The BEARINGS ARE NOT AT 150C...THATS THE POINT THAT HTHS IS MEASURED AT

For crying out loud, if you want to control your thick/thin thread, at least get your facts straight.