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Old 03-31-2013, 11:17 AM   #381
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Marin's friend says it takes less power to pump the oil (fluid) around. Don't buy that at all. It's the viscosity that requires power to move the fluid. Has nothing to do w slipperiness or lubricity. If syn takes less power to move through the system it's a lower viscosity fluid .... that's all. Put lower viscosity dino oil in and lower levels of power will be required. Nothing to do w syn oil.

However extreme ranges of multi-vis (frequently associated w syn oil) will lower the pumping friction for a short time warming up. When the VI improvers are less effective the oil will thin out. But if dino oil is the same viscosity when warmed up ....... no reduction in friction or temperature will result. But w extreme multi-vis VI improvers are probably employed and if they "wear out" or fail in any way an overall reduction in viscosity will result and lower viscosity will result in less heat and lower friction. But that will happen w dino oil in the same way. But lower viscosity will result in a lesser ability for the oil (dino or syn) to keep the metal parts from contacting each other. But w the syn oil running longer change intervals more time will tend to break down the viscosity improvers and it's possible or even likely that the viscosity of syn oil could or would suffer from extended change intervals.
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Old 03-31-2013, 12:02 PM   #382
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When the VI improvers are less effective the oil will thin out. But if dino oil is the same viscosity when warmed up ....... no reduction in friction or temperature will result. But w extreme multi-vis VI improvers are probably employed and if they "wear out" or fail in any way an overall reduction in viscosity will result and lower viscosity will result in less heat and lower friction. But that will happen w dino oil in the same way. But lower viscosity will result in a lesser ability for the oil (dino or syn) to keep the metal parts from contacting each other. But w the syn oil running longer change intervals more time will tend to break down the viscosity improvers and it's possible or even likely that the viscosity of syn oil could or would suffer from extended change intervals.
No offense intended, Eric, but I'm totally confused!
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Old 03-31-2013, 01:27 PM   #383
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Marin's friend says it takes less power to pump the oil (fluid) around. Don't buy that at all. It's the viscosity that requires power to move the fluid. Has nothing to do w slipperiness or lubricity.
While it's not my area of expertise, I don't think you can separate viscosity from lubricity. They are tied together. And it seems totally logical to me that if something is more "slippery," it will be easier to move, which means it will take less energy to move it. This holds true if you are trying to slide a piano across a floor or move a fluid through the narrow passages in an engine block.

And if it takes less energy to move it, the creation of that energy will generate less heat, be it in your body while moving the piano or in your engine as it moves the lubricating oil around through it.

Reducing friction and thus the resistance to movement is a factor of both lubricity (slipperiness if you will) and viscosity (density or "thickness"). The two work hand in hand to create the lubricating and flow characteristics of the fluid, in this case oil.

That's my take on it anyway. If my engine-industry friend has a comment on this particular aspect of the topic I will pass it on.
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Old 03-31-2013, 01:42 PM   #384
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I received this today in an e-mail from a friend whose career is installing, servicing, and maintaining marine engines of all kinds in everything from recreational production boats to custom yachts. I had commented to him on the topic of this thread and here is his reply.

You all can certainly comment on what he wrote but as I possess but one ten thousandth of one percent of his engine experience and knowledge I am in no position to either defend or refute it other than to say it sure makes sense to me.

----------------------

Many people believe that almost all of the heat produced by a diesel engine comes from combustion. In fact, they may be interested to learn that friction losses can amount to as high as 10 percent of an engine's heat rejection.

Synthetics flow much easier at low temperatures. They also flow much easier at operating temperature so, yes, they do reduce friction by a measurable amount and require less power to pump the stuff around. That reduction is reflected in less heat produced by friction and fuel burn. The piston ring to cylinder contact is responsible for about 50 percent of the friction losses (friction produced heat) and the bearings provide another 30 percent or so.

The bottom line is that synthetic lube will lower engine heat production and by extension,temperature. But, and this is the big but, if the cooling system is functioning properly with adequate margins for fouling, high sea temperature, and loss of efficiency from pump wear or other normal conditions, the difference would be lost in the noise.

The two or three degrees you mentioned is what I would call noise. There are other issues that make that visible and those issues could be a cooling system or installation that has zero margin, a difference in bearing clearances, ring pressure (how tight in the cylinders)block casting roughness, a single bearing running hotter than the others (we measure individual bearing temps in large engines rather than assume an average based on measuring oil temp) or just normal manufacturing tolerances. That is why there is a range of allowable temperatures rather than a single figure.

Someone else changing to synthetic might see a temperature change if their engine is operating at the upper limits of its margin of heat rejection, or see nothing at all if the system is operating at the lower margin or in the middle. By system, I don't mean just cooling system, I mean the boat and its auxiliaries as a complete system in the sense of physics.



-------------------------------


Good post all excellent points.... Temperature range is a key here not the exact gauge reading , Now lets go back to fuel vs oil for possible causes of high range temp for a sec... lets use round #s not exact figures for speed and ease, Syn vs dino for starts... lets say synth will reduce friction heat load by 10% over dino ... we will use 250*F for oil temp so... that would be a 25*F heat reduction to the engine oil cooler. That's a good thing. Now lets look @ fuel, Out of spec diesel fuel that is low in cetane can raise exhaust gas temps by as much as 10%..... So average turbo EGTs under load, lets say 1200*F @ 10% is 120*F rise in heat load to the fresh water cooling heat exchanger.That's a bad thing, Now lets use the 90 / 10 ratio for source of heat in our diesel that the heat exchangers must deal with also the fact that the OP is looking @ his temp gauge for the fresh water side of the cooling system.... Does fuel quality have anything to do a high range temp problem...??? Although oil quality has a lot to do with diesel performance and life span.... Fuel quality plays a bigger role by a ratio of 80 /20 ... and we are just scratching the surface on fuel quality...
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Old 03-31-2013, 01:43 PM   #385
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Marin,
I spoze it's possible there's a boundary layer thing going on but I really don't think so. Water has low lubricity but flows in a tube well and oil flows less well. I don't think there connected Marin. But I can relate to you're thinking so.

Craig S,
"synth will reduce friction heat load by 10% over dino" Do you really think so??? I'm thinking it's more like 2 or 3% ... if at all. There must be many studies that show very closely what the difference in lubricity is. Can't help but be many. Could some skilled searcher find something for us to relate to?
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Old 03-31-2013, 02:49 PM   #386
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Several sources I have read from engineering or petroleum companies suggest that syn oils reduce operating temps by 10-15 degrees over dino oils but in an engine application it may never be seen due to the cooling system.

mainly due to reduced viscosity because higher flow rates transmit the heat faster plus some have better heat transfer properties in general.
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Old 03-31-2013, 07:40 PM   #387
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Marin,
I spoze it's possible there's a boundary layer thing going on but I really don't think so. Water has low lubricity but flows in a tube well and oil flows less well. I don't think there connected Marin. But I can relate to you're thinking so.

Craig S,
"synth will reduce friction heat load by 10% over dino" Do you really think so??? I'm thinking it's more like 2 or 3% ... if at all. There must be many studies that show very closely what the difference in lubricity is. Can't help but be many. Could some skilled searcher find something for us to relate to?

Eric, 2 or 3% would be closer but the end result would still hold true, The scary Mobil 1 guy said the EGTs were @ 1600*F in that test In these times its harder to fend thru engineering fact or friction.
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Old 03-31-2013, 09:27 PM   #388
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The bigger question is whether any of these few percentage points actually matter based on the life expectancy of the iron lumps in the belly of our boats? Moreover, based on the much higher increase in the cost difference? That's still the most BASIC question that I have yet seen answered and what keeps me from making the switch. When companies that produce regular oil stop making it and completely switch to synth because it is proven superior and regular oil is obsolete, I will be sold, but as it stands now, I feel like they are just offering a gourmet product for little more than a promise and that you are ok paying top-dollar for it. And that's fine.
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Old 03-31-2013, 09:47 PM   #389
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Walt

While helping yourself to ascertain reason(s) for the too high heat in your engine... I look forward to your syn – vs – dino oil test that may help us all toward further defining what syn – vs – dino oil usage could accomplish.

Clearly there have become no “fool proof actualizations” of syn – vs – dino usage parameters accounted for throughout this thread; amongst the many, many 1st hand inputs, thoughtful conjectures, and even some 2nd hand input stemming from supposed "experts" that one or more of us may know... there are simply too many well-meaning contradictions constantly being thrown around. Also, www links have hundreds of manufacturers’ broad range comparisons or completely separate test accountings as well as some outsourced “clinical studies” supposedly performed by engineers and under strict conditions that also leave a lot to be desired as compared to truly beneficial and absolutely undeniable proofs from long term, accurate “blind test studies”.

Therefore – results from your synthetic oil – vs – hydrocarbon oil test will add even more good will input to our continuing search for the best engine and gear box lubrication products on the market.

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Old 03-31-2013, 10:00 PM   #390
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Tom B,
That's a great summary of what I would call basic reality.

psneeld,
If the operating temp (you don't say oil or coolant) is actually significantly lower 85% of the trawler operators here should forget about syn oil as using it would have the effect of even lower loading relative to oil temp and that's the issue w under loading.
OR the reverse could be true in that the syn oil is so clean that keeping tars, varnishes and soot in the lubricant suspended would be almost a non issue. Perhaps underloading would be a non issue at ANY engine speed and this could be a really good reason for those loading at less than 40% to switch to syn oil. I hadn't thought of it before but this could be a really good reason to go synthetic. I operate a bit over 50% load so wouldn't benefit but for the many here that do there could be a real benefit for using synthetic oil.
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Old 04-01-2013, 08:42 AM   #391
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I've had Cummins come out and thoroughly go through those items and many more, several times! As I stated earlier, the thermostat has been changed, a new sender installed, coolant has been changed, new Impeller, exchangers pulled and cleaned and 2 gages hooked up so as to compare both readings. (one on the panel and one with alligator clips to the sender.) The boat was tested after each of these changes, all to no avail. I talked with Tony Athens at Boat diesel, their Cummins guru, and he suggested all the things we've tried so far. Even though the temp is within the Cummins specs, (203 max) Tony and my local Cummins rep both agree that my engine runs hotter than normal. dwhatty of this forum also has a 32 IG powered by the same make and model as my engine and his runs cooler as does another forum member in Florida who has a Nordic Tug with a Cummins 330B.

The only thing left to try is synthetic. (Capthead's experience) I have nothing to lose except a few bucks which will not kill me.

There's a lot of advice given on TF, possibly misguided and uninformed, which RickB used to point out. I think my experiment, no matter the result, will shed more light on the use of synthetics. Note: I don't expect to prove anything to those that run 40 year old Lehmans. They will have to do that themselves.

To quote Steve McQueen in the movie, Tom Horn, "you have my last word on the matter."
You hang in there Walt. Just for the record, thermostats are not precise pieces of equipment. Not only does their performance curve follow a hysteresis loop, and is not linear, but the temp of the raw water flowing through the system has a small impact. I see a lower temp when the water is colder, like this weekend where she was running just a degree or two above 80C, when in peak of summer it moves closer to 90C. I make that point so you do make your comparisons close enough together for the raw water temp not to be a factor, or someone might prick the bubble.
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Old 04-01-2013, 11:45 AM   #392
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..... but the temp of the raw water flowing through the system has a small impact....... I see a lower temp when the water is colder,...... I make that point so you do make your comparisons close enough together for the raw water temp not to be a factor.......
Peter:
Thanks for your interest and suggestions. I did elude to "sea water temp" in post #292. I probably did not explain myself clearly enough but it is my intent to run the tests within 24 hours of one another. I want the only "change" in the testing environment to be the "oil." An effort will be made to keep all the other components of the testing environment, including sea water temp, as close as possible.
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Old 04-01-2013, 12:27 PM   #393
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On the subject of the "heat" produced by an engine, my industry friend had this to say that might help clarify things a bit....

---------

There is a difference between heat and temperature. Heat is the amount of energy in a substance, temperature is the measure of how fast the molecules in that substance are moving. That is why you can pinch the 1000C flame of a candle with impunity but will end up in the hospital if you rest your hand on a 200C frying pan.

When we talk about reducing the heat produced by 10 percent, we are talking about the BTUs produced and rejected from the system. We are not talking about reducing the temperature by 10 percent.

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Old 04-01-2013, 01:56 PM   #394
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On the subject of the "heat" produced by an engine, my industry friend had this to say that might help clarify things a bit....

---------

There is a difference between heat and temperature. Heat is the amount of energy in a substance, temperature is the measure of how fast the molecules in that substance are moving. That is why you can pinch the 1000C flame of a candle with impunity but will end up in the hospital if you rest your hand on a 200C frying pan.

When we talk about reducing the heat produced by 10 percent, we are talking about the BTUs produced and rejected from the system. We are not talking about reducing the temperature by 10 percent.

---------------------
And, "The Plot Thickens"! No oil viscosity pun intended...
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Old 04-01-2013, 02:27 PM   #395
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Wow, this might see 500 posts.
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Old 04-07-2013, 10:37 PM   #396
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I called my brother who is a chemical engineer and he is going to ask about why I got less sheen after changing to synthetic. When he gets back I'll share what he found.
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Old 04-21-2013, 01:50 PM   #397
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Worth a look - Good links on oils and other items!

HTTP://WWW.Carbibles.com.
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Old 04-21-2013, 02:33 PM   #398
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I was reading along agreeing with the whole article and all of a sudden it became an infomercial for Amsoil

The fact about black death and sludge should open a few minds. Toyota and Ford learned the hard way. Just sayin.
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Old 04-21-2013, 02:58 PM   #399
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Art,
This paragraph may interest some here as much concern and baugh humbug thoughts have been kicked around extensively for some time. All should be aware that there is something to this business of under loading. Not often do we hear something that can be taken to the bank but this blurb seems to have some real value.

From Art's link;

"Inland Marine Diesels (and certain road vehicles under special conditions) can (and do) glaze their bores due the low cylinder wall temperatures causing the oil (and more importantly the additive pack) to undergo a chemical change to a varnish-like substance. The low temperature is caused by operating under light load for long periods.
This is related to engine design, some engines being nearly immune to it and others susceptible. The old Sherpa van diesel engines were notorious for this problem. The "cure" (such as it is) is to use a low API specification oil, such as CC. Certain engine manufacturers/marinisers are now marketing the API CC oil for this purpose under their own name (and at a premium). You'll find some modern engines where its industrial/vehicle manual states API CF and the marinised manual states API CC/CD. {Thanks to Tony Brooks for this information.}

Read more: http://www.carbibles.com/engineoil_bible.html#ixzz2R7pm9CWs"

Cap,
There are other commercial intrusions other than Amsoil and a lot of different logos. I'm not keen on Amsoil but I don't think they're guilty here.
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Old 04-21-2013, 04:05 PM   #400
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I was reading along agreeing with the whole article and all of a sudden it became an infomercial for Amsoil

The fact about black death and sludge should open a few minds. Toyota and Ford learned the hard way. Just sayin.
I still (currently) believe in dino, high detergent, HD Valvoline 5-40W diesel oil and 4 OZ ZDDP additive at oil change and 4 more OZ 1/2 way in between changes for classic gasoline engines with flat tappets. Of which I have 4 in use and one more this summer to go into use on a ski boat (I hope). That said, I keep my eyes and ears open for what I feel could be any type of lube improvements for any need!
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