| Author | Message | ||
     Majicmak |
BuelieDan, The cylinder of an ABC engine is ground on a taper. There is no clearance at the top. With the piston and sleeve out of the motor you can load the piston through the bottom and it will slide to the top and get stuck. These things realy scream too. For a short time. Saro, It is a two stroke glow plug motor. The piston is aluminum with no ring. The cylinder sleeve is brass, chrome plated on the inside for wear. They run on Alcahol, Nitro methane and Castor oil. A ring motor running on synthetic oil will outlast one of these 3/1 Mak | ||
| Majicmak |
Levig, The term CENTISTOKES is not one that I am famillar with. Can I take it to mean that synthetic oil is more compressable that mineral oil? Mak | ||
| Blake |
Leveg: (in my best Ronnie Reagan) "There you go again." "The point we have all missed, is that oil viscosity increases by an enormous amount under pressure. That statement is VERY misleading and actually blatantly untrue in the context you presented. Do you really know what your friend is saying? Do you know the difference between kinematic viscosity and absolute viscosity? Do you know the base units comprising a centistoke? Do you know that oil is incompressible? Do you know the difference between an extreme pressure additive and motor oil? Do you know if transmission fluid is an extreme pressure lubricant? "When a load of 80,000 psi is applied to this oil in operation, it's viscosity can increase to around 270,000 centistokes. (that's why an oil film is strong enough to deform metal bearings). By contrast, a synthetic version of the same oil under the same load may only increase it's viscosity to around 7,000 centistokes." Words like "can" and "may" hold little weight in a technical statement like that. Furthermore, your example contradicts your main point. You say synthetic should not be used to break in an engine because it prevents proper wearing in. Your example claims that synthetics will have a lower local viscosity under pressure and thus a thinner film. But, Leveg, a thinner film would allow quicker wearing in of cylinder wall and piston ring asperities. That is opposite of what you are claiming. As far as how the oil exerts enough pressure on roller bearings to support the forces required to deform them (elastohydrodynamic lubrication), you need to understand that "deform" is a relative term in this context and that doctoral dissertations can fall short of explaining the mechanisms involved in such a scenario. I can assure you that there is FAR more to characterizing elastohydrodynamic lubrication than simply understanding the viscosity of the lubricant. Can you say where in an IC engine the lubricant loading approaches anywhere near 80,000 psi? What would you say the lubricant loading on the cylinder wall might be? Don't know? I'll tell you then. It's on the order of 10 to 100 psi. Your impressive sounding dialogue is technical quakery. Your argument flies in the face of what ALL the knowledgeable experts and industry people practice. Maybe you'd care to name the lubrication company who's technical chief gave you the information you posted. Do they produce a significant synthetic product line? I am guessing no. All the modern multi-million dollar equipment I have EVER seen, including $40M radio telescope systems, massive offshore generators, offshore cranes, offshore propulsion systems, nuclear reactor equipment, steam turbine generators, military heavy equipment, heavy industrial earthmoving equipment, draglines, all state of the art racing engines, and my Buell... ALL use synthetic oil. I just don't see how you can argue against that. Most of the above applications include roller bearings as well as gearboxes and speed reducers (EP applications). The redline claim re turbine lubrication... More shady marketing. There is NO specific approval or rejection by any turbine/jet engine manufacturer as to the form/type of the base stock used in an approved turbine lubricant. The lubricant must simply pass certain evaluation performance tests. Mobil produces more than one synthetic turbine oil. What type of base do you think they use? Do you know the difference between the lubricant requirements for a jet engine turbine compared to a gasoline engine? Which must endure higher temperatures? What are the differences in viscosity requirements? What are the operational temperatures? Why should we even care if our motor oil shared a common base with a turbine lubricant? Is that necessarily a positive aspect? I'll tell you what it is. It's shady marketing. It sounds impressive. In the end, it is meaningless half truths designed to get your money. One BIG reason I stick with Mobil-1 is their very well established integrity. They simply don't submit to shady marketing. I respect them for that. Fact: Synthetics are no more slippery than mineral oils of the same viscosity. | ||
| Blake |
Mak: The centistoke is a metric designation of kinematic viscosity (n). Kinematic viscosity is equal to absolute viscosity (m) divided by the fluid's mass density. One centistoke is equal to 0.01cm2/s. The comparable designation for absolute viscosity is the centipoise with one centipoise equaling 0.01g/cm2•s. The behavior Leveg related might occur at the microscopic level on a molecular scale for EP lubricants. It does NOT occur in any fashion or to any extent significant enough to effect the overall viscosity seen by an IC engine's lubrication system. It certainly does not occur between cylinder wall and piston rings. Leveg: Yes, viscosity of petroleum oils can decrease through contamination (water) and certain types of physical breakdown like that due to excessive shear stresses. It can also significantly increase in viscosity through thermal breakdown where the shorter chained lighter hydrocarbons burn off leaving the heavier longer, MORE VISCOUS ones. Running an air cooled engine on a hot summer day... which do you think is more likely to occur? Hans: What are you thinking now?  I'll say it again... LET'S RIDE!!! This is getting stooooooopid! Court! Please fine this guy!  Blake | ||
| Blake |
Leveg: Just one more for ya re the Redline claim... Do you know the difference between the polyalphaolefin base that Mobil uses and the polyol ester that Redline uses? You're gonna love this... They are one in the same. Yep... polyol ester = polyalphaolefin = PAO Do you think Redline synthesizes their own base stock? Let's see, the founders were television broadcast technicians. Nope, Redline buys their synthetic base. Who do you suppose makes it? Could it beeeeee... M o b i l ? I dunno, but it's possible ain't it? "Toyota Racing Development. Factory race division - Highly respected !" Yeah, in the field of racing, maybe. Not in the field of lubricant development. | ||
| Hans |
Hi Blake: What should I think: My computer started to smell badly: Melting plastic. Don`t know what plastic. The smell before sparks kill electric thingies. Electric fan did not move. That is what I got, looking for problems with ball bearings. Unscrewed all what could be unscrewed and cleaned the fan with help of the vacuum cleaner and painters brush. And what: "Sleeves bearings" was printed on the fan, whatever that maybe. However: after re-assembling without any lubrication all works fine again. And about oil and ball bearings? I keep asking myself what could be the origin of the hype between owners of the old Laverda`s,with roller and ball bearings in crankshaft and camshaft, to use never synthetics. Maybe only because the early automotive synthetics were not available in the prescribed viscosity for the Laverda engines. Hans. | ||
| Aaron |
You guys are more stubborn than me  Prediction: synthetics have been widely available for what, 20 years? I predict it'll be another 20 years before they're widely accepted as superior. The stages of truth take time. | ||
| Blake |
 Clinton Synthetic Oil! Guaranteed to penetrate and slicker than anything!  | ||
| Buelliedan |
In my 2 years here at BadWeb I learned one important lesson..... NEVER, I repeat NEVER try to argue with Blake about oils. You will lose, but in the end you will learn something if you listen!! Dan Catching up to Aaron, and I have an S3!! | ||
| Reepicheep |
Hans... the sleeve bearing fans are junk. Any mom and pop computer store (or web shop) will have stacks of replacement fans... all of which should be ball bearing. Depending on your CPU, running it with no fan or an impared fan can kill it in just a few minutes (worst case) or slow it down significantly (best case)... don't ignore it. Bill "who only runs synthetic in his Athalon due to the higher thermal stresses of modern CPU's" | ||
| Aaron |
e-mail I just got from Ashland oil co (Valvoline): "In order for the engine seals and rings to break in properly, recommend not using a synthetic oil for break in. For more information, please call our technical hotline at 1-800-354-8957, thank you." The plot thickens. I think it's up to SAE 60. AW | ||
| S2no1 |
Went on a beautiful ride in the fog and drizzle today. Much more fun than this discussion. Very alive the feeling. Oil, had some in bike so ok. Arvel  | ||
| Hans |
Bill, Thanks for your concern, but it was the fan of the AC transformer. However, your words will set me on the move for an replacement with ball bearings. I think that those fans are more difficult to find while people are not supposed to open the AC box. I have saved my fan heaters several times from the trashcan with a spray of WD40 on the axle or even contact cleaner just what came first in hand. Stuck engines bad. Lubricating good.  Hans. | ||
| Leveg |
I’ll try just once more. Hopefully some of you will get something from this. Blake, I think your interest is in just being argumentative. You’re not interested in learning anything new, you just want to look smart to the group, so you flick through your engineering books looking for technical phrases to confuse, then add an unhealthy helping of sarcasm. Firstly, the example I gave was just that - an example. But the discussion was about viscosity, not EP oils. The ability of an oil to increase it’s viscosity under load (viscosity pressure coefficient) is a basic of lubrication systems. It is totally independent of EP additives which are designed to assist during shock loading and extreme pressure metal to metal contact. They are irrelevant to this discussion, and you are using them to confuse. The reason I used words like ‘can’ and ‘may’ was because I was not referring to a specific oil, but stating the general properties of oils. Now, here’s one for you. Can you tell me the lubricant load encountered by the roller at the point of contact in a roller main bearing engine (like a Buell) on the firing stroke? I have never argued ‘against’ synthetics. In fact I have said they are superior in almost all areas, except in the lubrication of roller bearings in extreme use. You said “Your impressive sounding dialogue is technical quackery” I say take a look in the mirror. You said “Toyota Racing Development. Factory race division - Highly respected ! Yeah, in the field of racing, maybe. Not in the field of lubricant development.” What has that got to do with the ability of their engineers to know how to break their race engines in? Yes, I do know the difference between a Polyol Ester and a Polyalphaolefin, but you obviously don’t, if you think they’re the same thing. Polyalphaolefin is produced by reacting Ethylene gas into Decene molecules. Polyol esters are created by reacting an acid with an alcohol. If you ring Mobil and ask, I believe you will find that a part of their ‘Tri-synthetic’ formula is actually Hydroprocessed mineral oil. Yes good old Dino oil. Maybe that’s why Aaron doesn’t have any trouble breaking in his engines on it. | ||
| Leveg |
By the way, the oil company I raced for definitely has a significant line of synthetics. In fact we helped them develop a synthetic diff oil that would handle the stress of a 3000 Horesepower / 2300 lb car that could cover 60 feet in less than a second. That's shock loading. It required a solid particle additive that had to be mixed in before the race. Real world experience - there's nothing like it. | ||
| Blake |
Leveg: Sorry if my enthusiastic debating offended you. It wasn't meant to. I do like a good debate though. What I detest are anecdotal arguments and regurgitation of marketing speal. Now that you've taken some time to uncover and share some interesting technical facts, I am learning a thing or two. And yes you have forced me to dust off and crack open my Mechanics of Fluids textbook and my Machine Design handbook. Thanks for that.   Back to the debate... Leveg, your point about the increase in viscosity IS very misleading. You offered your example (and it was stated for a specific type of oil was it not) as proof that synthetics are slipperier than mineral oils. Leveg, you then contended that the cylinder wall to piston ring benefitted from the same action. They do not. You took a very extreme and microscopic boundary layer condition and applied it in general to the entire IC engine lubrication system in trying to prove your contention. The fact is that the phenomenon you vaguely described does occur. However, it ONLY occurs within the infinitesimal boundary layer of the oil (a microscopic layer on the order of a molecule in thickness that adheres to each of the metalic bearing surfaces involved). It has no macroscopic (overall) effect on the viscous behavior of motor oil in an IC engine. It has no effect on the value of the viscosity coefficient one would use to design the lubrication system, or the engine's mechanical components. Why? Because the film thicknesses in an IC engine are far greater than a few molecules. So, if you want to say that... "Under extreme pressures not seen within an IC engine, the molecule thick boundary layer of a synthetic lubricant will be less viscous than that of it's comparable mineral oil" I might agree. It in NO way follows that synthetics are slipperier than mineral oils. I mentioned EP lubricants, because in your example you offered the performance of a transmission lubricant. Transmission lubricants usually contain significantly more EP additives than engine lubricants. You are correct though, the phenomenon does exist even in base oil stock. I misspoke if I said it did not. (not quackery, an honest mistake.) Worst case (maximum) roller bearing design pressures, even on the con rod needle bearings are no more than 4,000 psi. PAO and Esters... You are correct. I definitely lied. I should have said that Mobil-1 also uses the Ester base as part of their tri-synthetic base. According to Mobil... No hydrogenated mineral oil as you claim. I can see where an overstressed roller bearing could benefit from the extra boundary layer protection afforded by a higher viscosity pressure coefficient. I can see how a high power dragster, designed for a few dozen seconds of service might fit that scenario. No bearing that is designed for a normal (100K miles) service life should ever see such extreme stresses. If one did, it certainly wouldn't last as intended, no matter what the lubricant. So, back to our original point of debate... I still say than (clarifying) in a commercially produced IC engine, synthetic oil is no more slippery than mineral oil of the same viscosity at the same temperature.  | ||
| Aaron |
  There you have it ... a senior engineer with one of the largest oil companies in the world says "synthetics are not more slippery than mineral oils". This guy is more qualified to speak on the subject than all the rest of us put together. That's good enough for me. AW | ||
| Steveshakeshaft |
I have watched the lube oil threads here with interest for a while. I'd like to add a few observations of my own. Nailing my "colours to the mast", I am a Mechanical Engineer specialising in machinery development for the last 28 years. I have also ridden and maintained motorcycles for the last 30. Bearing failures- I am struggling to think of a single bearing (journal or rolling element) that I have seen fail due ONLY to an incorrect lube oil being used. I have seen them fail thru contamination, lack of oil/grease/fluid, poor fitting and a 100 other things etc... but never thru using the wrong oil on its own. In the field of mechanical engineering all I can generally say is "some oil" is better than "none"! Can roller bearings skid?- I Have seen this, once. It was on a top bearing of a vertical electric motor ( ~ 750kW). On a shop test this motor was heard squealing upon run down from the top bearing. That was my "reward" for balancing and rebuilding the motor so finely that the top roller bearing when running down didn't have enough residual load to roll the rollers. Examination in the lab clearly showed the smearing on the races and the marking on the rollers where they skidded. Can it happen in an IC engine? I doubt it very much, there is too much "going on" in there for me to conceive that happening. The only thing I could think of would be if in a big Vee engine like the Harleys, many riders like a very slow "potato, potato" tick over. I can just imagine that the high acceleration/decelerations combined with low load and very low oil feed at extremely low tick over **might** cause it in big end/main rollers?? I would also like to reflect on the lifetime of bearings used in industrial machinery (not unusual to have a life exceeding 100,000 hours). With bearings used in the automotive field. A bearing that lasts 100,000 miles you would think to have performed well? At an average speed of 40 miles per hour, how many hours running is that? 2500 hours. Sort of makes you think? Are base oils all the same?- Like Blake I am very sceptical of marketing claims and I tend to classify oils by industry standards rather than brand X, Y, or Z. I once had the priveledge of taking a tour around the largest motor oil blending/packing plant in Europe. The base oils and additives were all in bunkers and were fed to the blending/filling/packing machinery via a control room. I was told that (quite obviously) buying the base oils was done to spec and price. The base oils were just as likely to be from Texaco as Shell and BP or anyone else you care to name. At the other end of the packing line, where fork trucks were taking pallets of oil to trucks for shipping, you could see the labels clearly. Who's names were on the labels? You name it. It was there. So, my view is, given that it can be "anybodies oil" in the bunkers and "anybodies oil" in the can at the end of the line. What option do I have other than buy oil to industry specs and price! Sorry for going on a bit! Steve. | ||
| Hans |
Blake, I hear somewhere a bell ringing: "Worst case (maximum) roller bearing design pressures, even on the con rod needle bearings are no more than 4,000 psi." Do we need then not to know the contact path between the rollers and their pathway ? That are presumed to be lines without dimensions other than lenght. I would estimate the pression much higher, as the flattening of the needles or the hole in the pathway will only be very small. Are you sure you are right on that number? Stubbornhardheadedandboringbutneverthelesshans. | ||
| Leveg |
Blake I'm glad I have been able to offer you an enthusiast debate. It has been interesting. There are countless references everywhere you look that synthetic oils are slipperier, and although Aaron's post from a Mobil engineer would appear to be the final word on the subject, the fact is that the term slippery is not a clearly defined one when applied to engine oils. It can be affected by several properties of the oil, and dependent on the lubrication condition i.e. hydrodynamic, boundary,etc. If one oil can maintain film strength where another can't , it will reduce friction. -From a magazine article, and therefore questionable - "Synthetic oils have a higher film strength. It takes six times more pressure to squeeze synthetic oil from between two surfaces than conventional oil." -From 'Thermodynamics, combustion and engines. 1995 Brian E. Milton' - "It has been established that the principal cause of friction in reciprocating engines is at the piston/cylinder interface where up to 70% of the frictional losses occur. This is because the contact pressures between these components is high and because it is a difficult region to lubricate. As the piston approaches top dead centre, it's velocity reduces to zero and the hydrodynamic lift from the oil disappears. Thus this region is subject to high wear rates and high friction." If a synthetic oil of a given viscosity can provide an overall reduction in friction in an operating engine over an equivalent mineral oil, doesn't that make it more slippery? | ||
| Blake |
Hans: 4000 psi is PLENTY pressure to SIGNIFICANTLY elastically deform the bearing. Leveg: You got a point thar. Terms are somewhat nebulous. Still... not slipperier, but a superior lubricant cause it sticks around better.  Not sure that is actually true, as you allude to. I think the additives take care of that type of problem. Besides, the rings sure don't excert much pressure against the cylinder walls. I've compressed 'em by hand, ain't nuthin' to it. KY Jelly is "slipperier" than motor oil, but it is a poor engine lubricant. Steve: Great post, and information. So the vertical mounting orientation of the motor starved the ass end roller bearing causing it to skid? What lube plant did you tour in Europe? Blake | ||
| Leveg |
What about when the rings have combustion pressure behind them, or worse, detonation? | ||
| Steveshakeshaft |
Hi Blake. No, the skidding bearing on test was caused by very low levels of residual out of balance in the rotor, so as it slowed down the rollers had not enough force to roll properly. So roll-skid-roll-skid....... In the lab it looked like a text book skidding failure. The only one I've ever seen. Ofcourse, once the thing went into service, end of problem. Ran for at least three years without stopping. The lube oil blending plant was owned by Century Oils. They were taken over by Fuchs Petroleum of Germany. Incidentally, FWIW, Mobil have their very own blending/packing plant about 50 miles from there! Steve http://ukbeg.com steve@ukbeg.com | ||
| Blake |
Greg: The pressure of combustion would push the rings downwards against their seats. High pressure in combustion chamber, low pressure in crankcase; the rings would be pushed downwards.  Zat make sense? | ||
| Leveg |
Makes sense, but the combustion pressure also acts on the back of the ring to force it out against the bore (it is obviously excluded from acting on the face of the ring by it's contact with the bore). Drag racers drill a series of holes through the top of the piston intersecting with the back of the top ring groove to maximize this effect and reduce lag. You'll be glad to know that the following is not anecdotal. (I'm very careful about references now that I know how sharp you guys are). From 'The Internal Combustion Engine in Theory and Practice' by Charles Fayette Taylor:- Research shows that gas pressure in the ring grooves is about 50% of cylinder pressure behind the top ring, and 20% behind the second ring. The average force of friction on the power stroke is about twice that of the intake stroke. Aaron - hope you get a chance to talk to Valvoline for their take on engine break-in with synthetics. | ||
| Blake |
That possibility did cross my mind. It would seem to depend heavily on how tightly the rings were seating into the piston. Ron Dickey of Axtell has mentioned that combustion pressures can reach 1,000 psi; I think he was referring to streetable motorcycles. According to your 50% rule of thumb, the rings would see an extra 500 psi due to combustion pressures, so around 600 psi occuring at/near TDC. Hmmm, drilling holes in high performance pistons. Wild stuff that. | ||
| Aaron |
hope you get a chance to talk to Valvoline for their take on engine break-in with synthetics No, I didn't bother to call them, the e-mail I posted above made their postion clear. Gas porting pistons, yep, I've heard of it but never tried it. Why isn't it more popular? Are there trade-offs? | ||
| Leveg |
Aaron Gas porting pistons is an option offered by most piston companies - Ross, Venolia, etc. It is generally only used on high R.P.M. naturally aspirated engines for Drag Racing i.e. short duration use. I believe that on anything else, it would result in high cylinder/ring wear. If you analyse it, some drag engines only turn over about 1000 times to cover a quarter mile, and are rebuilt after several passes, so maybe only 3-4000 revolutions under power between rebuilds. The reason I asked about Valvoline, is that it would be interesting to know what properties of their oil they felt made it unsuitable for break-in. Slipperiness, Film strength, Additives? | ||
| Blake |
Ignorance? | ||
| Buellzebub |
i wish i had teachers like you guys. i prolly woulda stayed in engineer school instead of becoming a stinkin technologist. very good discussion |
