If thick oil offers more protection, then isn't cold oil best?

[Foxtrot08]

Volume vs pressure.

That’s the simplest way to answer the question. Boyle’s law. Do you want more volume, or higher pressure?

 

[TomYoung]

Volume vs pressure.

That’s the simplest way to answer the question. Boyle’s law. Do you want more volume, or higher pressure?

I want more “r” !

 

[supton]

Volume vs pressure.

That’s the simplest way to answer the question. Boyle’s law. Do you want more volume, or higher pressure?

Both. I want my cake and to eat it too.

New take on the thick vs thin discussion... kinda hard to keep oil at ambient temperature when the coolant (and rest of the block) is well above that.

 

[cheesepuffs2]

New take on the thick vs thin discussion... kinda hard to keep oil at ambient temperature when the coolant (and rest of the block) is well above that.

You're looking at this too literally.

 

[supton]

You're looking at this too literally.

My recollection is that, for Ford's Ecoboost development, they were taking the engine, under load, and letting it warm up to good and hot. Then somehow changing coolant from 100C or whatever to like -40C so as to shock the block. Don't recall if they did likewise for engine oil.

So if there's a will there's a way. On a dyno it should be doable. That plot showing cylinder wall wear as a function of coolant temperature had to be measured somehow; so just do the same for wear vs cold start viscosity. [I just don't want to be the one to collect the data... nor pay for it.]

Edit: yes I know, it's Friday. I'm enjoying this one (while pretending to be working).

 

[Foxtrot08]

Both. I want my cake and to eat it too.

New take on the thick vs thin discussion... kinda hard to keep oil at ambient temperature when the coolant (and rest of the block) is well above that.

Your antiwear package won’t really work until it hits 160-180f anyways.

You’re not running a straight R&O oil.

 

[ChrisD46]

If I can’t achieve solid engine protection from M1 5W30 EP , M1 0W 30 ESP or M1 0W40 FS (all found at WM) then I’m going to look for another vehicle (lol !)

 

[Jetronic]

Your antiwear package won’t really work until it hits 160-180f anyways.

You’re not running a straight R&O oil.

and a thicker oil reaches 160-180f faster.... I question if a lot of engine oils even reach those temperatures during winter, on short to moderate drives.

 

[factorytuned2012]

Simply put No.

 

[Joba27n]

I'll help Op out here because I feel like his question is misunderstood... How thick is too thick of a viscosity before it's doing more harm than good.

This is a story I heard from my co-worker and fellow mechanic who is also a thickie... allegedly his elderly father took some new synthetic 20w-50 motor oil that was kicking around and did an oil change on his truck with it in the summer. Apparently a tank or two of gas later the engine had oil pressure issues, took it in to the dealership and the main and conrod bearings were discoloured and heavily worn. Not shredded, just worn and discoloured. It was either a 5.4 or 5.0 Ford in an F150.. I don't remember. He told them what happened and they helped him out by getting it covered under warranty but the reason the mechanic on the job provided the customer off the record was that apparently those engines have too tight a tolerance for such a thick oil and that 40 wt is the max they can reliably run.

I wasn't there and i'm skeptical of that reasoning but I fully trust my coworker and have no hands on experience with the engine in question so I'm not gonna comment further. Just throwing this out there of me hearing about a case of lubricant being too thick to application.

 

[OVERKILL]

I'll help Op out here because I feel like his question is misunderstood... How thick is too thick of a viscosity before it's doing more harm than good.

This is a story I heard from my co-worker and fellow mechanic who is also a thickie... allegedly his elderly father took some new synthetic 20w-50 motor oil that was kicking around and did an oil change on his truck with it in the summer. Apparently a tank or two of gas later the engine had oil pressure issues, took it in to the dealership and the main and conrod bearings were discoloured and heavily worn. Not shredded, just worn and discoloured. It was either a 5.4 or 5.0 Ford in an F150.. I don't remember. He told them what happened and they helped him out by getting it covered under warranty but the reason the mechanic on the job provided the customer off the record was that apparently those engines have too tight a tolerance for such a thick oil and that 40 wt is the max they can reliably run.

I wasn't there and i'm skeptical of that reasoning but I fully trust my coworker and have no hands on experience with the engine in question so I'm not gonna comment further. Just throwing this out there of me hearing about a case of lubricant being too thick to application.

Considering the Coyote spec'd both 5W-20 and 5W-50 depending on whether you had the "Track Pack" option pack or not (same engine, same internals) that story sounds a bit far fetched.

Also, clearances on the Modulars aren't any tighter than on the Windsor engines. Most engine clearances are pretty similar across a variety of brands, it's been that way for decades. The 5.7L HEMI that spec's 0W-20 has the same clearances as the 6.4L HEMI that spec's 0W-40.

 

[chris719]

Let's assume what you are saying is true. What downsides could be caused by oil that is never at full operating temperature in an internal combustion engine?

Everything is about trade-offs.

Among other things, the antiwear package does not function the same at low temps. According to journal papers, ZDDP doesn't really work well until it gets near 170 F or so.

 

[ZeeOSix]

Part of wear protection comes from the AW/AF additives and the tribofilm they create on parts, and some of those don't start working well until the oil is at full operating temperature.

 

[ZeeOSix]

My point is that I read all the time here how "going thicker will never cause damage to an engine" but I don't see how that can be stated as an absolute with no ceiling. There has to be a point where the drawbacks outweigh to benefit. Imagine an oil as thick as molasses. Would that really provide more protection than a 30 grade if it can't flow freely through the bearings? It's "thick" though, so thick must mean good, right? At some point the bearin clearances won't be able to accommodate the viscosity.

In the world of multi-viscosity motor oil ... that being xW-8 to xW-60 ... in those grade choices the highest HTHS oil will provide the most parts separation when just looking at if from a viscosity standpoint. There is no getting around the physics that more viscosity between two moving parts results in more MOFT between them - that's the whole key to lubrication and Tribology.

Obviously, the proper W rating for the cold start-up conditions are very important, and basically a separate lubrication aspect when choosing a motor oil. Getting proper lubrication to parts is critical to preventing engine wear and damage. If the oil is too cold to pump, then the engine very well could be damaged or at least experience more wear. The W grade rating defined by SAE J300 has been tweaked to help prevent any lack of cold start lubrication. Of course engine oiling system design is the other part of the equation. It needs to be properly designed to give full lubrication in all use conditions assuming the right oil viscosity is used.

 

[ZeeOSix]

Being separated by a little or separated by a little more is still separated.

And being separated by more results in more wear protection headroom. Why run on the ragged edge if you can mitigate that some. That's the whole purpose of say going up a grade for anything specified as 0W-20 or less.

 

[ZeeOSix]

f two parts are not touching between two times due to being separated completely by an oil film, there is wear occurring? Let’s exclude corrosive wear or extremely minute removal of metal from oil flowing by.

The only parts inside an ICE that are in full hydrodynamic lubrication almost all the time are journal bearings - until the HTHS gets too low and the MOFT goes to zero ... then you get excessive journal bearing wear. Everything else is in boundary or mix-lubrication realms. But higher viscosity will even help those parts some because the higher viscosity will still help provide more separaration for those parts too.

 

[ZeeOSix]

Volume vs pressure.

That’s the simplest way to answer the question. Boyle’s law. Do you want more volume, or higher pressure?

Getting the volume to the parts needing lubrication is the key ... the PD oil pump ensures that. Even parts like journal bearings don't actually need pressure to operate properly - they create their own high pressure oil wedge (their MOFT) to keep them separated just from them rotating.. The oil pressure is only there to make the oil move to the parts. In a fixed flow resistance system, it takes more pressure to make more oil flow volume. You can't have flow volume without pressure in an ICE oiling system.

 

[ZeeOSix]

Considering the Coyote spec'd both 5W-20 and 5W-50 depending on whether you had the "Track Pack" option pack or not (same engine, same internals) that story sounds a bit far fetched.

Yes, that story is far fetched. Most likely the issue was a lubrication problem, not the 20W-50 used in the summer.

As you know, I've posted in other threads both the rod and crank journal bearing clearances from the factory service manual for the Coyote - below is a summary I put together. And as you point out, the Coyote is speced to run anything from 5W-20 to 5W-50. They run very tight bearing clearances. The whole "engines are designed around the oil viscosity" claim by some ranks in the top 5 misconceptions in the automotive world. Same goes with motorcycle engines ... they all typically spec 10W-40 viscosity, and they also have very tight journal bearing clearance specs.

 

[cheesepuffs2]

I'll help Op out here because I feel like his question is misunderstood... How thick is too thick of a viscosity before it's doing more harm than good.

This is a story I heard from my co-worker and fellow mechanic who is also a thickie... allegedly his elderly father took some new synthetic 20w-50 motor oil that was kicking around and did an oil change on his truck with it in the summer. Apparently a tank or two of gas later the engine had oil pressure issues, took it in to the dealership and the main and conrod bearings were discoloured and heavily worn. Not shredded, just worn and discoloured. It was either a 5.4 or 5.0 Ford in an F150.. I don't remember. He told them what happened and they helped him out by getting it covered under warranty but the reason the mechanic on the job provided the customer off the record was that apparently those engines have too tight a tolerance for such a thick oil and that 40 wt is the max they can reliably run.

I wasn't there and i'm skeptical of that reasoning but I fully trust my coworker and have no hands on experience with the engine in question so I'm not gonna comment further. Just throwing this out there of me hearing about a case of lubricant being too thick to application.

Yes, this is exactly what I'm talking about, and Foxtrot summed it up as well. You can't just say "thick is best, you can't go too thick, thicker just means better separation of moving parts at all costs".

There absolutely has to be a breakover point where it becomes a detriment. I'm not saying that I know where that point is, and certainly it would vary by engine. But this is a prime example of what I mean, and it's why I'm skeptical of owners of new cars calling for 0w-8 and 0W-16 that are like, "I'm putting 0W-40 in it for the higher HTHS". I get that they mean well, but that isn't necessarily the best choice without having more information.

 

[cheesepuffs2]

There is no getting around the physics that more viscosity between two moving parts results in more MOFT between them - that's the whole key to lubrication and Tribology.

But the first word in MOFT is "minimum". If the minimum oil film thickness is enough to prevent appreciable wear, then why do we need excess head-room on that minimum? It gets to a point where it's overcompensation that ultimately just provides more parasitic drag on the engine for no tangible gain, and that isn't smart tribilogy either.

"As thick as necessary, as thin as possible".