No they aren't. Engines but be tolerant of a wide range of viscosities because of the impact ambient temperature has on it. This is the largest single factor in impacting what viscosity the engine sees when it is started.
Pressure is the artifact of resistance to flow. We see pressure on the gauge because the positive displacement pump is attempting to cram a specific volume of oil through the system. The heavier that oil is, the more difficult this is, so the artifact is increased pressure. The amount of pressure required reduces as the oil thins with heat, which is why hot oil pressure is lower from cold oil pressure.
When the oil is extremely thick, this can result in the pump going into bypass, which means some of that volume is shunted back to the feed-side and not forced through the engine.
Oil feed orifices are designed to bleed-off the necessary volume from the main gallery(ies) to feed their branches. So for example, on a pushrod engine, the feeds to the branches that feed the lifters and pressurize/lubricate the lifter bores are sized for that purposes are considerably smaller than the main gallery itself.
Oil is pumped, so "flow" is not important. Oils pumps are positive displacement, which means that each turn of the gears displaces a specific amount of oil. How that oil flows under gravity is irrelevant to that function as long as the oil can make its way up the pick-up. In a "sling" situation (small B&S engine) pump bypass doesn't even come into play because there isn't one.
No, the numbers on the bottle tell us two things:
1. The number in front of the W (Winter rating) of the lubricant is the ability for the oil to:
a. Make its way up the pick-up tube; be pumpable. This is MRV
b. Have a minimal impact on the cranking speed of the engine. This is CCS
2. The number after the W is representative of the "hot viscosity" of the oil and is measured at 100C. Each grade has a range assigned to it.
How the oil will "drain back down the drain holes" isn't factored into this scenario. The 100C figure is used to determine the amount of "cushion" in hydrodynamic situations, HTHS tells you that visc under higher temperature, and high shear, and the other figure, the Winter rating, tells you whether the oil is appropriate for the prevailing ambient conditions/starting temperature.
That makes zero sense. The oil pump doesn't know, or care, whether the oil is conventional or synthetic, as long as it can pump it, it will. Since an oil pump, not on the relief, displaces the same volume of oil per revolution, even the viscosity is mostly irrelevant here. While a lower viscosity oil will increase bearing side-leakage an engine would need to be completely destroyed; bearing clearances would have to be past "toss a rod through the side" and you'd have no oil pressure in the scenario he's trying to conjure up.
Viscosity is viscosity and doesn't depend on whether the oil is conventional or synthetic as well. A 5w-30 synthetic behaves the same as a 5w-30 conventional.
Again, wildly incorrect. A synthetic and conventional oil of the same viscosity flow the same, and the engine would have to be well beyond the ability to run for clearances to be large enough to allow all of the oil volume to escape. Of course the artifact of that would be no oil pressure. Engines aren't designed around conventional or synthetic or even a particularly viscosity, but they may have a certain hot viscosity in mind as part of the bearing design. For example, an engine designed to run on 0w-16, 0w-12 or 0w-8 will have wider bearings because of the greatly reduced HTHS viscosity of the lubricant. Because of the reduced load carrying capacity of the lubricant, the bearing area must be increased to prevent metal-to-metal contact.
And yet here you have Ford that spec'd both 5w-20 and 5w-50 for the same engine, lol. Engines are incredibly tolerant (necessarily so, due to the impact temperature has on viscosity, as outlined earlier) of a wide range of viscosities and as long as you don't use an oil with an inappropriate Winter rating (a 20w-50 when it's -25C vs a 5w-50) and don't go thinner than the allowable range (don't run a 0w-12 in an xW-20 application) the engine isn't going to care.
A red herring, strawman and generous hyperbole all wrapped into one here, oh my! No response warranted for this detour.
Gross generalizations and wild speculation, not worth addressing, it isn't even clear what he's addressing here.
It would have had nothing to do with the oil being synthetic or not and would be due to the oils having friction modifiers in them (which energy conserving oils do). Motorcycle oils are not friction modified, the reason of course is shared sumps. There are plenty of full synthetic motorcycle oils that are wholly appropriate.
Again, synthetics are not "freer flowing". While they often have a better Winter rating, this has nothing to do with operating viscosity. Not understanding the subject and then trotting out what amounts to urban legend isn't helping here. Using an oil not designed for motorcycle and shared sump applications can be problematic, but whether that lubricant is conventional or synthetic is wholly irrelevant.
And yet here we have somebody who clearly doesn't understand the basics
Given the above observation, that's quite an ironic statement.
And yet he still doesn't understand viscosity. Clearly, this was money wasted if that's what was supposed to be learned.
But he said it will flow "too good" and explode, what's this pedal back? Now it's just going to cost more money?
Nope, they were developed for cold weather (arctic) and jet engine use, as conventional oils wouldn't hold up in turbine applications, oxidizing rapidly and breaking down. The Germans also developed the Fischer-Tropsch process during WWII, employing coal gasification to produce both fuel and lubricants because they were resource constrained. This process is now employed by Shell to produce their GTL synthetic base stocks and various other products from methane.
AMSOIL was started by a pilot who saw the superior characteristics of the synthetic lubricants developed for turbines and worked with Hatco to develop the first API-approved synthetic lubricant for automotive applications. This was followed by Mobil (Mobil 1) whose history of developing arctic and jet turbine oils using synthetic base stocks resulted in them using that knowledge to develop one for automotive use.
Oil plays a tremendously important role in cooling an air cooled engine, as you don't have any coolant, so the only thing taking heat away from parts is the oil.
Not sure what F1 has to do with this, it is far from the only racing venue to employ synthetic lubricants, they are used universally in everything from drag racing to 24hr races, Nascar....etc.
Wow, this guy should write fiction, he's much better at it than giving oil advice.
Synthetic oils were a far cry from "exotic" once Mobil 1 and AMSOIL became available. The ability to improve conventional base oil quality (Group II) and improvements to PPD's and VII polymers was a natural evolution of lubricants and in no way depended on synthetics. Synthetic oils didn't see any form of wide adoption until the long life approvals were developed in Europe and they worked to extend drain intervals, which necessitated the use of PAO to hold up.
GM developed a "Corvette" spec, which was carried by Mobil 1, and GM and Mobil had a development partnership that benefited both parties.
Semi-synthetics were borne of the philosophy of providing some of the advantages PAO-based synthetic offered (better low temperature performance, greater oxidation resistance...etc) while keeping the cost down. Ergo, some synthetic base stocks were blended in with conventional base stocks which improved the overall performance. There's nothing BS about the name.
He seems to be wildly confused on the different base oil tiers and how that applies to oil labeling.
Group I is the lowest (solvent refined) base oil. Introduce hydrocracking and hydroprocessing and you get a purer end product with lower wax, which in turn has better cold temp performance and oxidation resistance, this is Group II. Refinements to this process have resulted in Group II+, which is an unofficial designation. Severe hydrotreating results in a very pure base oil with a higher VI and even better oxidation resistance and low temperature performance, this is Group III and is considered synthetic in most parts of the world that aren't Germany.
A semi-synthetic can be mixed with Group III, PAO, POE or AN's or a combination of those products. There is nothing that dictates how it is blended.
Modern synthetic oils of course are a blend of multiple bases, the slate for which includes:
1. Group III
Mobil products are typically a blend of the bottom 4, while Shell synthetic oils typically use #2, there are still lubricants where they appear to use their Group III base (XHVI) oils. Even though GTL technically falls under the Group III category, it's performance is slotted between your typical Group III and PAO.
I assume he's trying to refer to PAO, which is produced using ethylene gas. This is still something that comes out of the distillation tree, but the production of the building blocks to produce PAO through this process means it has absolutely no slack wax in it and thus has extremely good cold temperature performance and oxidation resistance. These base oils have high natural VI's, which means less VII polymer is needed.
Mobil 1 EP 0w-20 is a predominantly PAO-based lubricant. Most commercial 0w-40's contain some percentage of PAO and Mobil uses it in varying quantities in many, if not most of their lubricants that you can indeed pick up at your local parts store.
There are plenty of readily available synthetic oils that indeed use PAO and are sold under the "vollsynthetisches" designation in Germany, such as the Ravenol shown in my signature. AMSOIL also still uses PAO in their Signature Series line and Redline white bottle lubes are majority PAO.
Oils are of course designed to neutralize acids and hold these byproducts in suspension. Oils that are designed for extended drain intervals have improvements made to these characteristics so indeed can be run considerably longer without risk of those contaminants falling out of suspension. Oil filters remove the particulate.
Not sure who he is responding to here but these tangential anecdotes are not at all germane to his earlier rants. That B&S engines are durable and wildly tolerant of abuse has nothing to do with that. And in terms of failure of understanding of the fundamentals, well.... we've been over that.
I'm definitely no quantum physics prof, but this is essentially word salad designed to hand wave away the fact that he doesn't understand pressurized lubrication or how a positive displacement oil pump operates. Bringing up quantum mechanics by mentioning valance imbalance (something to be discussed with reference to say manganites in terms of anode/cathode development for batteries for example, @JHZR2
is significantly better versed to speak on this bit than I am) isn't relevant here, neither is gravity or adhesion.
The polar nature of certain base oil molecules and additives is predominantly relevant with respect to non-pressure lubricated surfaces like cylinder walls, cam lobes...etc. Where you want to promote the maintenance of a film. This is particularly relevant to engines that sit for significant periods. Esters are quite polar and do a good job in this department, while PAO is not. Group I is also quite polar, but also has poor oxidation stability, amongst other detractors. Polar bases also have good solvency, which is why POE or lower group bases are blended with PAO to properly integrate the additive package.
Yet he wrote a novel arguing about it... I wonder if he is aware that this observation is, contextually, just introspection?
I wonder which way he thinks it works? Judging from his remarks on synthetic "flowing too freely" I'm inclined to think that he may be in the wrong camp.
Detergents are designed to keep particulate in suspension, this includes broken VII polymers, oxidation byproducts, combustion byproducts...etc. Dispersants are designed to prevent agglomeration, which would result in those products falling out of suspension.
While it is generally true that detergents are not designed to clean-up existing deposits, lubricants have been in fact advertised as being able to achieve that, which would be a function of the detergent and dispersant blend even if only by proxy, as if varnish or sludge is broken down and drawn into suspension via a mechanism such as the inclusion of an ester that does in fact clean, the role of those additives are to keep that in suspension, allowing larger particles to be captured by the oil filter.
A good example of this is my own series of runs with Mobil 1 in our Expedition, as well as @wwillson
recent experience with the HPL lubricant products where he saw significant carbonaceous build-up in his filter as the result of this process.
can of course expound on this further.