Thin to thick oil converts?

[tig1]

Originally Posted By: Shannow
But thinner reduces the minimum oil film thickness which isn't a good thing if load/temperature dictates.

see the advice re Ford/Chev re track use, and various other manufacturers regarding temperature and load/speed.


But for the average engine in a sedan that calls for 20Wt(perhaps millions of them)your scenario isn't relevant. In big hard use V8s then yes, I would agree with you. My son has a big block GM engine in his 2017 GMC Yukon(not hard use) that calls for 0-20. He now has 35K on the vehicle and all is well. Also if I had an engine calling for a 30Wt I would use 30. Same with 40wt. Life's simple that way.

 

[Saxon78]

Originally Posted By: Virtus_Probi

the big problem when people fail to change their oil for long periods is extreme thickening, as in the funny YouTube videos with long strings of rubbery looking stuff hanging out of drain holes.


Of course, you're right, in 60 000km the viscosity will finally rise again to a gelly mess.

But I was talking of OCI (Oil Change Interval), not of extreme cases of NCO (Never Change Oil)

Those people are not visiting this board, I suppose, that's why I didn't bother discussing the issue this far; I was sure that someone would do it, BTW

 

[FCD]

Originally Posted By: tig1
Originally Posted By: FordCapriDriver
Originally Posted By: tig1
Originally Posted By: aquariuscsm
Hey dblshock have you noticed any sluggishness in your Honda with the 0W40 compared to 0W20? With 0W20 in my Honda,it's so responsive that I just barely touch the accelerator and it REALLY goes. I've never actually had to put weight on it and depress it. Smooth and silent too!!


That's just one of several benefits of 0-20. I had a 1990 Ford Tempo that called for 5-30. I tried one oil change of M1 15-50. The engine was noticeably sluggish, so I drained it after one week. Also when I first tried M1 5-20 in 1978, I really noticed a much more responsive revving engine over the 10-40 Valvoline I had been using.

So we should all run 0W-20 in every car in the world?
All you ever do is regurgitate the same line, your anecdotal evidence is not useful as people on this board have a huge array of different cars and drive in different conditions... i could say from my anecdotal evidence that running 20w50 in my cars doesn't seem to do any difference compared to thinner grades, i can say from anecdotal that my dad used to run my Capri on M1 5W-20 in the winter in Finland and that it had a lot more valvetrain noise and burned through it pretty fast.
I prefer facts to personal experiences.


I actually recommend using the wt called for by the engine builders as my example of trying 15-50 in my 1990 Tempo. After one week of sluggish performance I went back to the OEM oil. That's my facts. However in the late 70s I did use the M1 5-20 vs the 10-40 called for and it performed very well for me in my six cyl Dodge engine. Again, my facts. As for your Dad's experience in a Capri, If the engine was poorly maintained, then yes a thinner oil would not be best.

By the way, while in the US Navy(1966) I was deployed to Rota, Spain with Patrol Squadron 11(VP11) for three months.

Ofcourse, the factory recomendation is the best to follow indeed.
50 grades will make an engine spec'd for 5w30 sluggish ofcourse, but my old Ford allows 20W-50 at any temp above freezing so i run that with zero issues.

 

[ChrisD46]

Hyundai / Kia owners manuals list three oil grades (non turbo) : 5W20 , 5W30 and 10W30 and state to consider season / ambient temps and finally towing considerations (if applicable) to be your oil grade guide . *With such owner's manual information it's hard not to choose 5W30 and not feel like you made the safe choice .
Originally Posted By: tig1
Originally Posted By: Shannow
But thinner reduces the minimum oil film thickness which isn't a good thing if load/temperature dictates.

see the advice re Ford/Chev re track use, and various other manufacturers regarding temperature and load/speed.


But for the average engine in a sedan that calls for 20Wt(perhaps millions of them)your scenario isn't relevant. In big hard use V8s then yes, I would agree with you. My son has a big block GM engine in his 2017 GMC Yukon(not hard use) that calls for 0-20. He now has 35K on the vehicle and all is well. Also if I had an engine calling for a 30Wt I would use 30. Same with 40wt. Life's simple that way.

 

[spasm3]

Originally Posted By: ChrisD46
Hyundai / Kia owners manuals list three oil grades (non turbo) : 5W20 , 5W30 and 10W30 and state to consider season / ambient temps and finally towing considerations (if applicable) to be your oil grade guide . *With such owner's manual information it's hard not to choose 5W30 and not feel like you made the safe choice .


Thats what i did.

 

[igs]

Originally Posted By: Virtus_Probi
Originally Posted By: zveroboy
Originally Posted By: FZ1
I agree. I prefer to run thicker but in oem grade oil.


Yep.

For the THIN fans: remember that, as the oil gets used along your OCI, viscosity goes one way: DOWN.

Shearing, fuel contamination and other degradation processes will finally turn a Xw-30, let's say, into a lower grade (Xw-20).
It's going thinner, not thicker , AFAIK.

Moreover, a 5w40, if overheating a little, may temporarely act like a 5w30 (viscosity goes down as the temperature increases). Not the other way around.
So "thicker" (within the engine producer's allowances) gives some long and short-term safety margin.

I don't have any advice to give, just underlining some facts.

Personally, with a lot of spirited driving (3500-5500 RPM), I stick with the heaviest grade allowed by the car's manual (5w40 in my case), and I'll always look for a "thick/heavy" 5w40 (higher HTHS/kV100), that still has an acceptably low CCS/MRV for easy cold-starts .

It's about finding the good compromise.

This is not true in the slightest...the big problem when people fail to change their oil for long periods is extreme thickening, as in the funny YouTube videos with long strings of rubbery looking stuff hanging out of drain holes.
XOM even gave us a graphic for their AP product in which they admit that those oils shear down faster than competitors, but supposedly also resist extreme thickening much longer.

That graph clearly shows viscosity dropping over time. It's not until the tail end of whatever time frame that is, 100k, 200k miles, that it thickens.

 

[Doug Hillary]

Hi,
zveroboy - one must be careful about generalisations

In my OTR vehicles I averaged 90kkms OCIs (5W-40 Syn HDEO) and the viscosity at 40C remained within acceptable limits!

 

[Ducked]

Originally Posted By: zveroboy

Originally Posted By: Virtus_Probi

the big problem when people fail to change their oil for long periods is extreme thickening, as in the funny YouTube videos with long strings of rubbery looking stuff hanging out of drain holes.


Of course, you're right, in 60 000km the viscosity will finally rise again to a gelly mess.

But I was talking of OCI (Oil Change Interval), not of extreme cases of NCO (Never Change Oil)

Those people are not visiting this board, I suppose,...



Dunno. I drop in from time to time.

I've got about 4 years on the oil, which is a roughly equal blend of straight 40 and 15W/40.

When it starts to look subjectively dodgy I'll change it, but I don't currently have any objective metrics.

Car specs straight 30 or 10W30.

 

[Virtus_Probi]

Originally Posted By: Doug Hillary
Hi,
zveroboy - one must be careful about generalisations

In my OTR vehicles I averaged 90kkms OCIs (5W-40 Syn HDEO) and the viscosity at 40C remained within acceptable limits!


Doug, that's very impressive...any bypass filtering involved in vehicles?

I know that thickening is generally not going to be a issue with a good oil and a reasonable OCI, but I know that some UOAs have been posted here that showed viscosity going out of spec HIGH with way less than 100kmiles! I know that somebody is going to call me on it and I'll have to be googling like crazy to back my words up...
BTW, I noted in my original post that the graph showed the M1 AP shearing/thinning faster than the other oils and have mentioned before that I was surprised that XOM was willing to advertise that. Seems that is the #1 BITOG beef about a number of M1 products, shearing too quickly...comes up in a lot of EB threads where some fuel dilution might be involved, too.

 

[Saxon78]

Originally Posted By: Doug Hillary

In my OTR vehicles I averaged 90kkms OCIs (5W-40 Syn HDEO) and the viscosity at 40C remained within acceptable limits!


Hi Doug, I confess that, being on a PCMO area, I was only focusing of PCMO change intervals. (max 30k km, let's say).
Anyway, your OTR OCIs are impressive.

I never thought of 40C kin. viscosity either, since the 100C is much closer to engine's operating temperature.

Off-topic question: what's the practical importance of 40C kViscosity? ( apart from calculating the Viscosity Index)?
Am I missing something?

 

[oil_film_movies]

zveroboy, If you look at a bunch of UOA's, you'll see oil many times thickens in normal OCI's. Oxidation will do that, often caused by poor quality anti-oxidants, high turbo heat, poor base oils. Short tripping can cause thickening due to acids creating insolubles too.
It does depend on the type of oil, and the type of usage or length of service for sure.

Virtus_Probi, that thinning from Mobil's graph isn't much. Current VII tech means it will happen, and that depends on severity of usage, as in when used in a Honda S2000 which shreds the molecules. Most engines do fine, and the engineers design for a bit of thinning at first.

 

[oil_film_movies]

Originally Posted By: zveroboy
Off-topic question: what's the practical importance of 40C kViscosity? ( apart from calculating the Viscosity Index)?
Am I missing something?
There have been engineering fuel efficiency studies which shows fuel is saved during the inevitable warm-up phase by using oils that are thinner at 40 degC. Sure the hot 100 degC or 150 degC viscosities are more important for minimum oil film thickness, but the 40 degC figures do show an oil can resist thickening as it gets colder, and even indicates how an oil will do at 0 degC or slightly below, important for fast effective flow at cold starts.

 

[Virtus_Probi]

Originally Posted By: oil_film_movies
...

Virtus_Probi, that thinning from Mobil's graph isn't much. Current VII tech means it will happen, and that depends on severity of usage, as in when used in a Honda S2000 which shreds the molecules. Most engines do fine, and the engineers design for a bit of thinning at first.


I agree, and I wouldn't be running M1 AP right now if I was really worried about it.
;^)

 

[Doug Hillary]

Hi,

Originally Posted By: zveroboy


I never thought of 40C kin. viscosity either, since the 100C is much closer to engine's operating temperature.

Off-topic question: what's the practical importance of 40C kViscosity? ( apart from calculating the Viscosity Index)?
Am I missing something?


It is common for OEMs to set viscosity limits for their products - in my OEM's case this was at 40C and allowed for a Max increase of 40% and a Max decrease of 15% over the original product's specification at that temp. Many engine families have a bulk oil temperature in the 80-100C range

Personally I've always used the lowest specified viscosity at the temperature specified by the Manufacturer

People may forget that 20W-50 was a specific lubricant viscosity developed by Duckhams (Q20-50) in 1958-9 to compensate for the poor technical attributes of the BMC Mini. It became the do-all lubricant for many !

 

[Shannow]

Originally Posted By: Doug Hillary
People may forget that 20W-50 was a specific lubricant viscosity developed by Duckhams (Q20-50) in 1958-9 to compensate for the poor technical attributes of the BMC Mini. It became the do-all lubricant for many !


Good to see you posting more Doug...

Similarly in these dscussions, I'm paitned as a thick advocate...the L67 in my Caprice is 20W50 as per the manual, but gets 5W30/10W30 A3/B4, my Nissan Navara was specced 15W40, got 5W30 A3/B4, the Captiva is specced 5W40, gets 5W30 Dexos2/C3.

 

[tig1]

Doug,
Likewise, good to hear from you. I appreciate your real life experience that you share with us.

 

[OVERKILL]

Originally Posted By: tig1
Doug,
Likewise, good to hear from you. I appreciate your real life experience that you share with us.


Indeed. Doug's extensive knowledge and vast portfolio of experience are greatly appreciated. I'm quite glad to see him posting more frequently again

 

[PimTac]

I also appreciate Doug's comments here. Very enlightening.

 

[wemay]

Wile e Coyote vs Road Runner
Tom vs Jerry
Bugs vs Elmer Fudd

Thick vs Thin motoroil

The eternal battle is just as real, almost as cartoonish but always fun.

 

[bbhero]

Great analogies Wemay. Hit the nail right on the head.