Running thinner oil, is my reasoning skewed?

ZeeOSix

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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.
Going too thin can be bad if the engine happens to be a bad fuel dilluter. Excessive fuel dilution can really lower viscosity drastically.
 
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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.
Well it isn't my intent to over-simplify or sound like I know what I'm talking about. I'll read and re-read what is going on so I can fine-tune what I know. I'm not a spokesperson, though I found a high performance oil I use, that company is @High Performance Lubricants and passion begets passion, I am amazed at how they select for what they blend, make, and do.

Better base oils are more conducive to a larger point spread without as many VIIs, which is desirable, since VIIs you generally want as least of them as possible? Let's see if I can adjust my understanding, and for all who read.
 

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Better base oils are more conducive to a larger point spread without as many VIIs, which is desirable, since VIIs you generally want as least of them as possible? Let's see if I can adjust my understanding, and for all who read.
Yes. And what you'll often see for OTS oils is that the narrower the spread, the cheaper they will go on the bases.
 
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Oil is only just thick enough to maintain film on all parts = engine will be fine forever.

Oil is only just not thick enough to maintain pressure = metal to metal contact(rod bearings for eg) engine gone within 100 miles.

My extremely simplified view on this sensitive topic (iam thin oil guy)
 

SR5

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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.
I was just talking about the regular Mustang, sorry I don't know much about the special ones.

Recently, when Ford first offered the Mustang for sale in Australia, after they stopped making the local Ford Falcon V8 sedan. They were very popular and probably became the most common sports car on the road overnight. This is probably the first time in decades that Ford Australia would sell you a new Mustang off the show room floor. Previous to that, you had to import your own as a one off. I think the popularity surprised even Ford.

Looking into the oil more, the 5.0 L V8 FM series from 2015-2018 uses 5W30, but the FN series from 2018-2022 is 5W20 in Australia now.
 
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ZeeOSix

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Oil is only just thick enough to maintain film on all parts = engine will be fine forever.

Oil is only just not thick enough to maintain pressure = metal to metal contact(rod bearings for eg) engine gone within 100 miles.

My extremely simplified view on this sensitive topic (iam thin oil guy)
How do you know the oil is "just thick enough" to maintain an adequate film/MOFT?

Not sure what you mean in your 2nd sentence. But oil thickness between moving parts and the oil pressure are not really connected.
 

ZeeOSix

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I was just talking about the regular Mustang, sorry I don't know much about the special ones.

Recently, when Ford first offered the Mustang for sale in Australia, after they stopped making the local Ford Falcon V8 sedan. They were very popular and probably became the most common sports car on the road overnight. This is probably the first time in decades that Ford Australia would sell you a new Mustang off the show room floor. Previous to that, you had to import your own as a one off. I think the popularity surprised even Ford.

Looking into the oil more, the 5.0 L V8 FM series from 2015-2018 uses 5W30, but the FN series from 2018-2022 is 5W20 in Australia now.
I would think the 2022 Mustang in Oz would also have the 5W-30 that is now specified in the 2022 Mustang in the USA.
 
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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.
You know whats crazy is the Focus RS was specced with 5w50. They were assuming the car was going to be tracked.
I vaguely remember oil temps being around 230f with a 0w30 after some canyon drives. I used the pink label euro edge
 

SR5

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I would think the 2022 Mustang in Oz would also have the 5W-30 that is now specified in the 2022 Mustang in the USA.
I'm sure you are correct, it looks to me like Ford Australia is following the mothership a lot closer now days.
 

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Thanks for the clarification. I keep hearing about the 10 psi/thousand rpm rule of thumb. Is there truth in it? Alos, does the Driven chart above have any value?
That’s a rule of thumb for small block Chevy engines, from about sixty years ago.

Mercedes gave you the required pressure. You quoted it. Use that.

Mercedes also told you what specification to use, and lists hundreds of oils that meet that specification, here: https://bevo.mercedes-benz.com/bevoonlinebak/229.5_en.html

Pick one.
 

M119

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The only 5W30 i've used for a full OCI was SHU 5W30 (A3/B4, MB229.5...). I wanted to try something even slightly thinner that wouldn't be a risk (as i said, most cars like mine seem to be running a 5/10W30 ILSAC in north america and still reach very high mileages) for a short OCI but even after thinking long and hard, i'll never feel good running something that's not on the Bevo list 229.1/3/5, even in my old tractor like motor.

I calculated that over 100,000 km i've tested 8 different oils. Here's my observations: They all run the same. 15W40 made my lifters slightly noisier when cold and with 5W30 the car felt peppier for the first few kilometers. Thinner oils tend to burn and leak more. The two oils that stand out so far are Total Quartz 5W40 and 10W40, both at 14.8 cSt, less of it goes past the valve stem seals, engine seems smoother and they both contain a good dose of moly and zinc. I think i've accomplished my bitoger's quest for the best oil for my application.

What is certain is that fuel consumption isn't effected much for highway driving and at the very least i haven't been able to see it. One day the E85 is E65 at the pump, an other day it is E75. Sometimes it rains (most of the time), sometimes it's dry. Any MPG benefit is hard to calculate. In fact i did my best tanks on 15W40 with slightly over inflated tires and a good engine tune-up.
 
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How do you know the oil is "just thick enough" to maintain an adequate film/MOFT?

Not sure what you mean in your 2nd sentence. But oil thickness between moving parts and the oil pressure are not really connected.
Its the most simplified example there is. I was told this by a guy who prepares race cars for CUP races. The cars where peugeot 206 gti 2l (EDM only)

Because it was a cup race you where not allowed to change anything mechanicaly. People sought after every last HP to get atleast some benefit.
The cars where specced for 5w40. On that spec the engines where fine even after being tracked hard while spending their first 15 years of their life as a road car and being put on a track with no rebuilt what soever.

Then some people went to 5w30 to try and get an slight HP advantage. Almost all of them spun a rod bearing shortly after the switch.
I dont know which brands/types/specs of oil. Just that engines failed after going down one viscosity step.

This was mainly because the oil got really hot, cars didnt have an oil cooler from factory and although them being a GTI model the 2l enige was just taken from one of their bigger models and never made for longlasting track conditions.

This is an extreme condition which road cars useally never see, however differences are useally only clearly seen in extreme conditions.
 

ZeeOSix

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Because it was a cup race you where not allowed to change anything mechanicaly. People sought after every last HP to get atleast some benefit.
The cars where specced for 5w40. On that spec the engines where fine even after being tracked hard while spending their first 15 years of their life as a road car and being put on a track with no rebuilt what soever.

Then some people went to 5w30 to try and get an slight HP advantage. Almost all of them spun a rod bearing shortly after the switch.
I dont know which brands/types/specs of oil. Just that engines failed after going down one viscosity step.

This was mainly because the oil got really hot, cars didnt have an oil cooler from factory and although them being a GTI model the 2l enige was just taken from one of their bigger models and never made for longlasting track conditions.
Guess that answers my question of: "How do you know the oil is "just thick enough" to maintain an adequate film/MOFT?" See post #60. ;)

This is an extreme condition which road cars useally never see, however differences are useally only clearly seen in extreme conditions.
True ... and nobody is going to be able to know the ramifications of going thinner and thinner with use on the streets (along with some slight extreme use) unless they start doing their own controlled wear study. The easiest way to mitigate any unknowns is to not use oils that are thinner than what the manufacturer calls out, or go up one grade from what the manufacturer recommends if you think you're on the ragged edge, and therefore want a bit more HTHS viscosity and MOFT headroom.
 

M119

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I was thinking about this, what are the driving conditions simulated in the M111FE test? I remember seeing this graph but i guess this test is more oriented towards short trips/city driving than long trips/highway. Also, i have trouble understanding if these results apply to just an engine or a whole car.


Image189.jpg
 

ZeeOSix

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I was thinking about this, what are the driving conditions simulated in the M111FE test? I remember seeing this graph but i guess this test is more oriented towards short trips/city driving than long trips/highway. Also, i have trouble understanding if these results apply to just an engine or a whole car.


View attachment 91223
Don't know ... could be just the engine since the test was to determine the effect on the engine's fuel consumption.

But whoever made the graph can't even make the top of the bars coincide correctly with the Y-axis scale ... 😄
 

M119

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Yes, uploaded the first one i saw but there are better versions of this graph. 😄

Indeed, i think 2.6% fuel economy seems huge for 5W30 vs 15W40 for a whole car moving down the road.
 
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I notice better throttle response and less drag until the oil is hot and isn't a minimum oil pressure required to maintain that wedge?
In that case you can probably go from 10w30 to 5w30 or from 5w20 to 0w20, but I wouldn't go from 5w30 to 5w20 just in case the weather gets hot and you have an emergency and needs to tow something heavy or go somewhere fast.
 

M119

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In that case you can probably go from 10w30 to 5w30 or from 5w20 to 0w20, but I wouldn't go from 5w30 to 5w20 just in case the weather gets hot and you have an emergency and needs to tow something heavy or go somewhere fast.
0W30 A3/B4 would be the thinnest i'd go. Might as well try a 0W40 but 0Wx are too expensive, more than twice as axpensive as a 5W40.
 
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