Running thinner oil, is my reasoning skewed?

OVERKILL

$100 Site Donor 2021
Joined
Apr 28, 2008
Messages
50,666
Location
Ontario, Canada
I don't remember a lot of fuel or especially low flash points (BS). The MC 5W-50 just seems really bad for shear. Some people claimed it was designed to do it like all the GF-1 5W-30 used to be. If that's the case why not just start out as a relatively thin 5W-40? Didn't make sense to me.
K, would have been nice to see some with real fuel % figures. I understand that oil shears, but I recall a lot of the M1 0w-40 shear hype was ultimately fuel dilution, and because some many use Blackstone for analysis, this wasn't being properly captured/represented.
 

SR5

Joined
Jul 7, 2015
Messages
6,488
Location
Down Under
Ford bumped the recommended viscosity spec from 5W-20 to 5W-30 on the 2021+ Coyote. No engine changes on the 2021 Coyote, and not sure if Ford is back specing for the older Coyotes. A lot of 2015+ Mustang owners run 5W-30 over 5W-20 anyway.
And Ford Australia only ever spec'd 5W30 in their fully imported V8 Mustang

Edit: already mentioned a few posts on
 
Last edited:

M119

Thread starter
Joined
Jan 3, 2020
Messages
776
Location
Brittany
OP,
which 5W30 did you end up using, was it the A5/B5 Ford 913-D oil?
It is. I drove a lot, maybe 1,000 km in a week and what i can say is that it was a bit less sluggish for the first 10 min of driving so i can see why it fits the average driver in terms of fuel economy but i barely do any short trips and my fuel consumption didn't improve at all. I'll admit that two tanks is nothing but chasing fuel economy through cSt and HTHS seems useless in my case. After all i was able to achieve my best tank on 15W40. Increasing tire pressure made so much more difference in every aspect. I had to see for myself what i've been reading on bitog for two years. 10W40 is back in the sump and i'll feel better when i'm stuck in traffic on scorching days. I've saved the 5W30 in a clean jug for my gf's Citroën's next OCI. What went in is Total Quartz 10W40 that i bought for 7 bucks. It has the highest moly and zinc i've ever seen an A3/B4, SN oil!
 
  • Like
Reactions: SR5

M119

Thread starter
Joined
Jan 3, 2020
Messages
776
Location
Brittany
Also, even in a short time it looked like it made every seal and gasket seep even more.
 

M119

Thread starter
Joined
Jan 3, 2020
Messages
776
Location
Brittany
Also, even in a short time it looked like it made every seal and gasket seep even more.
 
Joined
Jan 25, 2003
Messages
5,354
Location
Decatur AL USA
And Ford Australia only ever spec'd 5W30 in their fully imported V8 Mustang

Edit: already mentioned a few posts on

The Track Pack optioned cars (assuming that option was available) only got 5W-30? That would be interesting. Would be the first case I've heard of USA cars getting 50 Grade and Australia getting 30 Grade.
 

ZeeOSix

$100 site donor 2022
Joined
Jul 22, 2010
Messages
32,421
Location
PNW
The Track Pack optioned cars (assuming that option was available) only got 5W-30? That would be interesting. Would be the first case I've heard of USA cars getting 50 Grade and Australia getting 30 Grade.
Think he's talking about the 2015+ S550 Mustang (6th Gen), which was the first generation of Mustang with RH drive for export. I don't think 5W-50 was ever speced by Ford in the 2015+ Performance Pack Mustang. Rouse however speced 5W-50 when they do the supercharger upgrade. The GT500 may still spec 5W-50.
 
Last edited:
  • Like
Reactions: SR5
Joined
Jan 25, 2003
Messages
5,354
Location
Decatur AL USA
[
Think he's talking about the 2015+ S550 Mustang (6th Gen), which was the first generation of Mustang with RH drive for export. I don't think 5W-50 was ever speced by Ford in the 2015+ Performance Pack Mustang. Rouse however speced 5W-50 when they do the supercharger upgrade. The GT500 may still spec 5W-50.

I think they are Performance Package 1 & 2. I think the Track Pack ended with the '14. I don't know why but I thought Ford exported the '11-'14 (of course they may have required conversion in Austaliia). Regardless I get the point.
 
Joined
Nov 29, 2021
Messages
3,444
Yup, just took a while longer for the Euros to get onboard.
Excellent.

I do wonder, if the more efficient oils also help them wrangle every last horsepower out of an engine, due to the oil moving around easier or with less friction, or if that is nonsense.

I've gone the AEHaas route for a long time, inspired primarily by this board, on a long time quest to see the "thinnest" oil I could use without causing an issue and.. as unscientific and not able to be used as actual evidence as it is, I always thought I could feel "more power" - specifically in terms of an engine revving up faster, only change engine oil, or perhaps more freely if that is impossible or easier - on a thinner oil, I'm stuck on HTHS, just occurred to me how that may relate to MOFT.

I've sometimes thrown in a thicker oil, to try to contrast to what I think I know, and, sometimes engine seems to really like that too. So I don't know what to think.
 

ZeeOSix

$100 site donor 2022
Joined
Jul 22, 2010
Messages
32,421
Location
PNW
I do wonder, if the more efficient oils also help them wrangle every last horsepower out of an engine, due to the oil moving around easier or with less friction, or if that is nonsense.
When oil is at 200F+, there isn't really that much difference in viscosity so it would be hard to "feel a difference", espeically in a high powered engine. In a low powered engine it might be possible to tell a slight difference. You'd have to do some back to back dyno runs with different oils to measure actual differences. But going from say a xW-20 to a xW-30 isn't going to be any night and day difference. Going from xW-16 to xW-50 or 60 ... that would be more noticeable.

I've gone the AEHaas route for a long time, inspired primarily by this board, on a long time quest to see the "thinnest" oil I could use without causing an issue and.. as unscientific and not able to be used as actual evidence as it is, I always thought I could feel "more power" - specifically in terms of an engine revving up faster, only change engine oil, or perhaps more freely if that is impossible or easier - on a thinner oil, I'm stuck on HTHS, just occurred to me how that may relate to MOFT.
No engine is going to "blow-up" on a thinner oil. Pretty much every study on oil viscosity vs engine wear shows that thinner oil can certainly cause more wear between moving parts - something you many never detect from behind the wheel. HTHS is the viscosity at 150C (the high temp) at a shear rate of 1M/sec (the high shear), which is suppose to simulate what's going on inside a journal bearing at high RPM. MOFT is directly tied to the oil viscosity when all other factors are held constant - higher viscosity gives more MOFT. MOFT is the small film between moving parts that helps prevent metal-to-metal contact and wear. At some point, viscosity can become too low which makes MOFT too small ... result is metal-to-metal contact and increased wear. Been that way ever since tribology was invented.
 
Joined
Nov 29, 2021
Messages
3,444
When oil is at 200F+, there isn't really that much difference in viscosity so it would be hard to "feel a difference", espeically in a high powered engine. In a low powered engine it might be possible to tell a slight difference. You'd have to do some back to back dyno runs with different oils to measure actual differences. But going from say a xW-20 to a xW-30 isn't going to be any night and day difference. Going from xW-16 to xW-50 or 60 ... that would be more noticeable.


No engine is going to "blow-up" on a thinner oil. Pretty much every study on oil viscosity vs engine wear shows that thinner oil can certainly cause more wear between moving parts. HTHS is the viscosity at 150C (the high temp) at a shear rate of 1M/sec (the high shear), which is suppose to simulate what's going on inside a journal bearing at high RPM. MOFT is directly tied to the oil viscosity when all other factors are held constant - higher viscosity gives more MOFT. MOFT is the small film between moving parts that helps prevent metal-to-metal contact and wear. At some point, viscosity can become too low which makes MOFT to small ... result is metal-to-metal contact and increased wear. Been that way ever since tribology was invented.
Well my observations were always on what we could call low to medium-power engines, yes. I do like forced induction a lot and I've never had any kind of a fire breathing monster of an engine. It does seem a thicker oil (something 30 and up) is the "best" as far as offering long protection.. perhaps I have never used a truly "thin" 20.

Oil has gotten so good, I would have to ask what does and does not apply when it was believed your oil could be "too thin."
 

OVERKILL

$100 Site Donor 2021
Joined
Apr 28, 2008
Messages
50,666
Location
Ontario, Canada
Excellent.

I do wonder, if the more efficient oils also help them wrangle every last horsepower out of an engine, due to the oil moving around easier or with less friction, or if that is nonsense.

I've gone the AEHaas route for a long time, inspired primarily by this board, on a long time quest to see the "thinnest" oil I could use without causing an issue and.. as unscientific and not able to be used as actual evidence as it is, I always thought I could feel "more power" - specifically in terms of an engine revving up faster, only change engine oil, or perhaps more freely if that is impossible or easier - on a thinner oil, I'm stuck on HTHS, just occurred to me how that may relate to MOFT.

I've sometimes thrown in a thicker oil, to try to contrast to what I think I know, and, sometimes engine seems to really like that too. So I don't know what to think.
Haas is short tripping ultra high performance cars with massive sumps and not getting the oil up to temperature, or putting them under full load. You are NOT doing the same thing, lol.

At low oil temperatures and in-town driving (short tripping) a lower starting viscosity will reduce fuel consumption during warm-up. Once everything is up to temperature, the gains are close to non-existent.

You really have to go out of your way to cause damage with a heavier oil, basically, you'd need a no-pump situation, like maybe 20w-50 when it's -30C. However, if you want to fart around with 0w-8 or 0w-12 in a car that calls for an oil with an HTHS >2.6cP, you are far more likely to cause damage, might even be able to get a little rod peekaboo going on if that's your thing.
 
Joined
Dec 26, 2005
Messages
21,541
Location
Upper Midwest
You really have to go out of your way to cause damage with a heavier oil, basically, you'd need a no-pump situation, like maybe 20w-50 when it's -30C. However, if you want to fart around with 0w-8 or 0w-12 in a car that calls for an oil with an HTHS >2.6cP, you are for more likely to cause damage, might even be able to get a little rod peekaboo going on if that's your thing.
There are pictures.
 
Joined
Nov 29, 2021
Messages
3,444
Haas is short tripping ultra high performance cars with massive sumps and not getting the oil up to temperature, or putting them under full load. You are NOT doing the same thing, lol.

At low oil temperatures and in-town driving (short tripping) a lower starting viscosity will reduce fuel consumption during warm-up. Once everything is up to temperature, the gains are close to non-existent.

You really have to go out of your way to cause damage with a heavier oil, basically, you'd need a no-pump situation, like maybe 20w-50 when it's -30C. However, if you want to fart around with 0w-8 or 0w-12 in a car that calls for an oil with an HTHS >2.6cP, you are far more likely to cause damage, might even be able to get a little rod peekaboo going on if that's your thing.
No rod peek-a-boos as in. No good engine. Not good. I liked the idea of a thinner oil because, logic was, if you start thin, you stay thin, it won't thin further. Talk of 1. Base stocks (a better base stock won't shear?) and 2. Shearing, what oils stay in-grade and what don't.

I'm working soon so I may very well check back tomorrow. Rods staying in engines is always a good place to start. lol
 

OVERKILL

$100 Site Donor 2021
Joined
Apr 28, 2008
Messages
50,666
Location
Ontario, Canada
No rod peek-a-boos as in. No good engine. Not good. I liked the idea of a thinner oil because, logic was, if you start thin, you stay thin, it won't thin further. Talk of 1. Base stocks (a better base stock won't shear?) and 2. Shearing, what oils stay in-grade and what don't.

I'm working soon so I may very well check back tomorrow. Rods staying in engines is always a good place to start. lol
That's faulty thinking. Oils like TGMO with insanely high VI's (like 204 or whatever it was) are extremely thin and full of polymer, that's how you get a VI that high. The VI's of base oils are much, much lower, see my recent M1 EP 0w-20 thread.

Per the Mobil blending guides I've posted in the past, VII content can vary wildly depending on blending choices. Whenever folks try to over-simplify this (like you are doing here) invariably wrong conclusions are drawn. A 0w-40, which is a wide spread oil, can be blended using less VII using higher end base oils than a "cheap" 5w-30 for example. Even your average 10w-30, even though you can readily make one with no VII using PAO, isn't blended that way, they just use cheaper bases.
 

ZeeOSix

$100 site donor 2022
Joined
Jul 22, 2010
Messages
32,421
Location
PNW
Oil has gotten so good, I would have to ask what does and does not apply when it was believed your oil could be "too thin."
Viscosity is viscosity. The other thing that also factors in is the oil's "film strength" which is a function of the AF/AW additives. Film thickness (MOFT) due to viscosity is the first line of defense to prevent wear by keeping parts from rubbing together. Film strength is the second line of defense to mitigate wear once the parts do rub together. Film thickness and film strength are two separate animals. Everyone should read this article from Machinery Lubrication.

 
Last edited:

ZeeOSix

$100 site donor 2022
Joined
Jul 22, 2010
Messages
32,421
Location
PNW
There are pictures.
😄

1646255191241.jpeg
 
Top