Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-10-2019, 09:26 AM   #41
Guru
 
psneeld's Avatar
 
City: Ft Pierce
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 23,668
Seems like everyone is right...maybe that's a clue....


But where are the traditional oil is cheap and clean oil never hurt an engines guys this go around? I like every opinion under the sun with proof their theory is better.


Also where are the "my buddy never changed the oil in his Toyota corolla for 300,000 miles"...where are those guys?
__________________
Advertisement

psneeld is offline   Reply With Quote
Old 06-10-2019, 09:37 AM   #42
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
After reading the Cox Engineering link I ask;

Does any marine engine manufacturer recommend using synthetic lube oil?
__________________

__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-10-2019, 10:15 AM   #43
Technical Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,179
Quote:
Originally Posted by Nomad Willy View Post
After reading the Cox Engineering link I ask;

Does any marine engine manufacturer recommend using synthetic lube oil?
MAN high performance common rail engines require synthetic, at least the models I am familiar with. And I think only some syn oils meet the spec, so
kind of limited selection. Expensive oil changes!!

As far as I know, no others require it.

If I ran a high performance engine, and ran it hard, I probably would use syn whether they recommended it or not. Piston temps get pretty high on those when run hard and dino oil may (will) coke.

Run easy, don't see much benefit.
Ski in NC is offline   Reply With Quote
Old 06-10-2019, 10:26 AM   #44
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
In post #37 catalinajack wrote;

“An oil's viscosity rating, 15W-40 for example, only tells part of the story. The 15W number is the rating at 104 degrees. The 40 number is the rating at 212 degrees. At lower temperatures, synthetics do, in fact, pour more freely than do conventional oils despite the nominal SAE rating. It has to do with the molecular structure of the oil. Take a look at the YouTube video I attached. It was a demo performed by Shell Oil. It says all you need to know. Last I knew Shell sells synthetics and conventional so this demo holds no bias. There is a place for both types. Now don't go crazy when you see that the test was done at a temp of -40 degrees. There is a significant difference in pour characteristic at all cold temps. That is why synthetics are better at mitigating cold start-up wear at any temperature as they flow to the internals faster than synthetics. Now, the old wives tale is that 90% of engine wear occurs at start-up and warm-up. If one accepts that synthetics flow better than conventional at any temperature, one must conclude that any engine wil last longer using synthetics.”

When I bought my new Mitsu engine I got several oil filters from the engine supplier. Used then and was amazed that my horizontal mounted filter didn’t pour oil out of the filter when removing the filter. I’ve discovered that there was a check valve in the filter that kept the oil in the filter.
Since I used the last of the original filters I started buying filters from NAPA. Those filters do not have the check valve inside and as soon as I unscrew the filter more than a cup of oil comes gushing out.
Does this mean that for several seconds during start-up there is no oil pressure or oil delivery to the bearings? It would seem that oil to the bearings wouldn’t commence until the filter filled up. My logic says yes it should.
If oil flow to the bearings was critical it would seem nobody would manufacture filters that had an unnecessary lag time of oil pressure .. yet they do. Wouldn’t this de-bunk the notion of high engine wear at start-up. I would think so.

As to the “15w” in the viscosity rating (in catjack’s quote above) being taken at 104 degrees (I assume f) we start our engines between 40 and about 80 degrees f. Why do you buy oil with a high flow rating at low temps when you never start your engine at low temps. 10w30 oil was developed for cold starting of motor vehicles that wasn’t an issue above about 10 degrees f. The MV additives clearly aren’t needed in a trawler. Oil in the store is 98% intended for vehicles w engines exposed to outside air and the cold temps found there in the winter.

Re the synthetic oil the Cox guy (probably an engineer) synthetic isn’t recommended. But he dosn’t disclose what his boat is like either. A Donzi probably would benefit whereas a CHB not at all.

Re Ski’s 43 thank you much.
As I suspected.
Nomad Willy is offline   Reply With Quote
Old 06-10-2019, 10:41 AM   #45
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
Ski wrote on post #27,

“Going with syn does not automatically mean you can extend change intervals. Crud added to good oil still ends up being cruddy oil. Sampling is what tells the story. Even dino oil can go well beyond spec change intervals, and it has more to do with engine duty cycle and other stuff, not so much whether dino or syn.”

It would seem to me the only way to get rid of soot and particulate (grit) is to drain the oil when the engine is hot and most solids are in suspension.
How much abrasive wear is caused by this “dirt”?
Nomad Willy is offline   Reply With Quote
Old 06-10-2019, 10:52 AM   #46
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
Rufus wrote on post #25;
“I should have a better sense of the reduction in oil consumption after run time builds on the engines. I probably should have waited to report on my findings before posting, but I was genuinely amazed when I checked the dip sticks.”

Not so IMO.
Look at all the learning and interesting reading that has taken place since.
Nomad Willy is offline   Reply With Quote
Old 06-10-2019, 11:18 AM   #47
Guru
 
City: Northport
Join Date: Aug 2015
Posts: 1,834
Quote:
Originally Posted by Nomad Willy View Post
Ski wrote on post #27,

“Going with syn does not automatically mean you can extend change intervals. Crud added to good oil still ends up being cruddy oil. Sampling is what tells the story. Even dino oil can go well beyond spec change intervals, and it has more to do with engine duty cycle and other stuff, not so much whether dino or syn.”

It would seem to me the only way to get rid of soot and particulate (grit) is to drain the oil when the engine is hot and most solids are in suspension.
How much abrasive wear is caused by this “dirt”?
"It would seem to me the only way to get rid of soot and particulate (grit) is to drain the oil when the engine is hot and most solids are in suspension."

Some engines have centrifugal filters and/or bypass filters to help in this area.
smitty477 is offline   Reply With Quote
Old 06-11-2019, 06:12 AM   #48
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,943
"Oil in the store is 98% intended for vehicles w engines exposed to outside air and the cold temps found there in the winter."

Yes, mostly gasoline cars that do not require cranking speed to cause the fuel to be heated enough by compression to ignite.

"It would seem to me the only way to get rid of soot and particulate (grit) is to drain the oil when the engine is hot and most solids are in suspension."

Yes, heat counts but it takes a good long while for oil detergents to pull the deposited fines back into suspension.

Its great for the engine but not easy to muster the energy to yank 6 gal of oil, change the filter and refill after a long day of having fun!
FF is offline   Reply With Quote
Old 06-11-2019, 08:15 AM   #49
Guru
 
ranger42c's Avatar
 
City: Annapolis
Vessel Model: 58' Sedan Bridge
Join Date: Aug 2013
Posts: 5,509
Quote:
Originally Posted by Nomad Willy View Post
It would seem to me the only way to get rid of soot and particulate (grit) is to drain the oil when the engine is hot and most solids are in suspension.

FWIW...

My normal oil change regime starts with a barnacle run up the river and back... then I drain both engines, both gears, and genset once we're back at the dock.

The engine room is too warm at that point to fool with filters and refill, though, so that's the "tomorrow" part of the project.

-Chris
__________________
Chesapeake Bay, USA
ranger42c is offline   Reply With Quote
Old 06-11-2019, 08:50 AM   #50
Guru
 
City: Carefree, Arizona
Vessel Name: sunchaser V
Vessel Model: DeFever 48
Join Date: Apr 2008
Posts: 9,253
Good thread. A few early AM musings -

On Cat powered large dirt moving fleet operations I'm familiar with non synthetics rule. Why? Warranties and cost. As mentioned by Ski and others, synthetic oils don't automatically carry a longer run time.

Cat warranties, a very big deal, require the same oil change intervals. For large fleets, this translates to an increased lube cost of many hundreds of thousands of dollars per year to use synthetics. Hardly makes sense except for those extremely cold operations where synthetics can have the advantage for cold start times.

In our low hour diesel powered recreational marine world virtually any rational oil regime seems logical. Where it gets interesting is in high revving (aren't they all) gas outboards. Some are specked at synthetics for good reason. Given the number of outboards being produced, that is a lot of synthetic oil.
sunchaser is offline   Reply With Quote
Old 06-11-2019, 08:54 AM   #51
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
psneeld wrote;
“Seems like everyone is right...maybe that's a clue.... ”

How can that be .... but it is.

Some use synthetic some don’t.
Some use MV some don’t.

And w either approach nobody is going to notice their engine wearing out prematurely. As neeld says there are no winners or losers. But we all feel we’re just right enough to mention what we do and what we use and very very few probably change their ways or product.

One thing I would like to know is what (physically) is viscosity improver. I recall hearing it was tiny rubber balls. Could it be?
And on the same subject how long does the viscosity improver last. That is how long does the effects of the VI last. 10w30 is or starts out as 10 weight oil and gets stabilized so it has the viscosity of 10w oil when cold and 30w when hot. So if the VI looses it’s affect the oil is 10 weight .. not 30w.

I have heard down through the years that at change time some viscosity is lost. So what do we wind up with? 10w20? What I heard in the 70’s was worse than 10w20 resulted ... like maybe 10w15 or even 10w oil. Donee wann’a go WOT on 10w oil. And in recent years most seem to say “oh that’s just a thing of the past”. Well ... is it?
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-11-2019, 09:43 AM   #52
Guru
 
ranger42c's Avatar
 
City: Annapolis
Vessel Model: 58' Sedan Bridge
Join Date: Aug 2013
Posts: 5,509
Quote:
Originally Posted by sunchaser View Post
Good thread. A few early AM musings -

On Cat powered large dirt moving fleet operations I'm familiar with non synthetics rule. Why? Warranties and cost. As mentioned by Ski and others, synthetic oils don't automatically carry a longer run time.

Cat warranties, a very big deal, require the same oil change intervals. For large fleets, this translates to an increased lube cost of many hundreds of thousands of dollars per year to use synthetics. Hardly makes sense except for those extremely cold operations where synthetics can have the advantage for cold start times.

That has been my logic. Our engines are out of warranty, but the service manual still says every X hours or one year, whichever comes first. [My emphasis]

We usually hit that one year mark... gosh... every year... so any added longevity a synthetic like T6 might bring to the table... would be lost on us... at extra cost.

-Chris
__________________
Chesapeake Bay, USA
ranger42c is offline   Reply With Quote
Old 06-11-2019, 03:08 PM   #53
Guru
 
O C Diver's Avatar
 
City: Fort Myers, FL... Summers in Crisfield, MD
Vessel Name: Slow Hand
Vessel Model: Cherubini Independence 45
Join Date: Dec 2010
Posts: 10,122
Quote:
Originally Posted by catalinajack View Post
If the oil analysis on your charter boat comes back "good for continued use" why do you not believe your oil analysis report? I do understand that looking at that black oil is disconcerting but the oil analyses do not lie. However, I have sometimes changed the oil on my Chevy Duramax "just because" even though I really do not need to do that. I did that once at 900 hours even though the test showed no need to do so. That truck still starts and runs as the the I bought it 17 years ago and 292,000 miles.
Regarding my charter boat, when an engine goes 50 hours without consuming oil, and then starts consuming a quart every trip or so, I have to assume something has changed with the oil. Assuming it will never be better than when it's new, I have to assume the chance isn't a positive one. An oil change is under $100; a rebuild is around $10,000. I consider it a fairly logical decision.

An oil change on my pickup is around $40. I believe changing the oil every 5,000 miles will get me to 500,000 with the original turbo. Maybe synthetic will get your Chevy there. Guess we will have to wait and see if your truck makes it.

Ted
__________________
Blog: mvslowhand.com
I'm tired of fast moves, I've got a slow groove, on my mind.....
I want to spend some time, Not come and go in a heated rush.....
"Slow Hand" by The Pointer Sisters
O C Diver is offline   Reply With Quote
Old 06-14-2019, 12:55 PM   #54
Guru
 
City: LI or Fla
Join Date: Jul 2013
Posts: 1,148
I've actually had opposite results on syn oil that was put in my performance car engine 383 full roller used a bit of oil with syn and none with dino.

Pretty much all new cars are coming full syn now, that 0w number always gives me pause when I pick it up...
Marlinmike is offline   Reply With Quote
Old 06-14-2019, 01:41 PM   #55
Senior Member
 
City: port orchard, wa
Vessel Name: skybird
Vessel Model: skookum/one off
Join Date: Oct 2007
Posts: 140
from years of car/truck/boat experience, amsoil is the best full synthetic i`ve found, and10/30 is the best multi-grade! amsoil now makes a 10/30 for diesels! on the shaft vibration problem, all shafts, over 10 ft long, need a center bearing ours is 14 ft, and we put a center bearing behind the 'no drip' shaft seal...voila, no problems! our volvo 70B sits on the enging bed, with a 1/2" rubber pad to cushion it, with 2, 9" lag screws on each side holding it down...no so called motor mounts, it never gets out of allignment!...clyde
clyde is offline   Reply With Quote
Old 06-14-2019, 02:07 PM   #56
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
Clyde,
Some used Amsoil with their ultralights that used two stroke engines w high performance pipes at very high temps and running for long periods at WOT. High temps from as lean as possible for max power on air cooled engines. Some or more stuck their engines running Amsoil so I’ve steered clear of it. But that was in the late 70’s and early 80’s. So Amsiol has had lots of time to perfect their product. Also the fliers may have stuck their engines for other reasons like cyl head temp gauge not right ect. I used Bel-Ray motorcycle racing oil.
Now I lean toward Mobile-1.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-14-2019, 02:10 PM   #57
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
Quote:
Originally Posted by Marlinmike View Post
I've actually had opposite results on syn oil that was put in my performance car engine 383 full roller used a bit of oil with syn and none with dino.

Pretty much all new cars are coming full syn now, that 0w number always gives me pause when I pick it up...
I think it's all related to the shrinking seal additive.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-14-2019, 09:24 PM   #58
Senior Member
 
Civilitas's Avatar
 
City: PNW/Seattle-ish
Vessel Name: M/V Peter Iredale ;)
Vessel Model: rusting hulk
Join Date: Feb 2018
Posts: 128
Clearing up a mistatement repeated above might help get at the viscosity questions still open.

Quote:
Originally Posted by CatalinaJack
An oil's viscosity rating, 15W-40 for example, only tells part of the story. The 15W number is the rating at 104 degrees. The 40 number is the rating at 212 degrees.
Neither of those statements are correct. "15w" is the "winter" rating of the oil - "w" in a multi-grade oil refers to it's "winter" characteristics. This is a measure of pumpability/cranking viscosity at various winter temperatures. "15w" means it meets the spec (3,500cP) at -15c. Same for "20w", "10w," "5w". The "5" step increments are inverse around the -15c. Like this:

0w -30C (-22F)
5w -25C (-13F)
10w -20C (-4F)
15w -15C (5F)
20w -10C (14F)
25w -5C (23F)
30w 0C (32F)

The warm rating, "30," "40" etc. is viscosity taken at 104F/40C, not 212F.

In the chart above, the oil meets the winter rating and then VII - viscosity index improvers - are added to artificially thicken the oil. They are not durable, do not lubricate, and for oils with a wide viscosity spread (5w-40, e.g.), can be a large part of the oil by weight and volume.

if you take good look a the values above, you can see that unless you routinely start your engine with the engine room below freezing, you are wasting valuable lubrication capability by not running straight-weight oil. You are also gaining no "cold start" benefits.

Nomad Willy asked above about VII's being rubber. In the past, they were. A petroleum engineer explained to a group of us that in fact, in the 80s, they actually recycled tennis shoe soles by grinding them to fine dust and adding them to oil. Nowadays, they are far more highly engineered synthetic molecules, but still the same principal.

Quote:
Originally Posted by NomadWilly
And on the same subject how long does the viscosity improver last. That is how long does the effects of the VI last. 10w30 is or starts out as 10 weight oil and gets stabilized so it has the viscosity of 10w oil when cold and 30w when hot. So if the VI looses it’s affect the oil is 10 weight .. not 30w.
This is pretty engine-specific. How hot the oil runs on average and in unique spots, how much shear is experienced in different sections of the engine (internal gears, etc.), total oil volume, presence or not of a turbo, etc. all effect this. Some engines are really easy on oil, and others can chew up the VIIs in short order because of design characteristics.

Gas engines I know better; so let me give an example there - there are gas engines on the road that will destroy an average 5w-30 motor oil in 5 to 6k miles. The same engines can run happily 10k miles on higher quality 10w-30 synthetic (Yes I'm looking at you, Toyota 1mz-fe V6).
Civilitas is offline   Reply With Quote
Old 06-14-2019, 09:48 PM   #59
Guru
 
Nomad Willy's Avatar
 
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,114
OK great post Cavilitas.

I thought if I posted the rubber ball thing someone that had more up to date info would come forth. Thanks.
And as stated before I’m keen on minimizing the VI additives. Only reason I get away w running straight 30w oil in my old car is that I warm it up for 2-5 minutes before driving off. And of course I warm up my boat before slipping the lines. About 5 minutes there too.

In the powerhouse I worked in we ran a 16x20” x 8 cyl turbo diesel on straight 30w Delo. Had a 300 gallon dry sump and heated and circulated the lube oil for 24hrs before starting. Same w coolant. No need for MV there .. and we didn’t use it.
__________________
Eric

North Western Washington State USA
Nomad Willy is offline   Reply With Quote
Old 06-15-2019, 06:34 AM   #60
Guru
 
catalinajack's Avatar
 
City: Edgewater, MD
Vessel Name: Catalina Jack
Vessel Model: Defever 44
Join Date: Nov 2011
Posts: 2,435
With respect Civilitas, let me clear up your misstatements.



Quote:
Originally Posted by Civilitas View Post
Clearing up a mistatement repeated above might help get at the viscosity questions still open.



Neither of those statements are correct. "15w" is the "winter" rating of the oil - "w" in a multi-grade oil refers to it's "winter" characteristics. This is a measure of pumpability/cranking viscosity at various winter temperatures. "15w" means it meets the spec (3,500cP) at -15c. Same for "20w", "10w," "5w". The "5" step increments are inverse around the -15c. Like this:



0w -30C (-22F)
5w -25C (-13F)
10w -20C (-4F)
15w -15C (5F)
20w -10C (14F)
25w -5C (23F)
30w 0C (32F)

The warm rating, "30," "40" etc. is viscosity taken at 104F/40C, not 212F.


The high temp rating is, indeed, measured at 212F. I refer you to Wikipedia https://en.wikipedia.org/wiki/Motor_oil.



"A single-grade engine oil, as defined by SAE J300, cannot use a polymeric viscosity index improver (VII, also viscosity modifier, VM) additive. SAE J300 has established eleven viscosity grades, of which six are considered Winter-grades and given a W designation. The 11 viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. These numbers are often referred to as the "weight" of a motor oil, and single-grade motor oils are often called "straight-weight" oils. For single winter grade oils, the dynamic viscosity is measured at different cold temperatures, specified in J300 depending on the viscosity grade, in units of mPa·s, or the equivalent older non-SI units, centipoise (abbreviated cP), using two different test methods. They are the cold-cranking simulator (ASTM D5293) and the mini-rotary viscometer (ASTM D4684). Based on the coldest temperature the oil passes at, that oil is graded as SAE viscosity grade 0W, 5W, 10W, 15W, 20W, or 25W. The lower the viscosity grade, the lower the temperature the oil can pass. For example, if an oil passes at the specifications for 10W and 5W, but fails for 0W, then that oil must be labeled as an SAE 5W. That oil cannot be labeled as either 0W or 10W.
For single non-winter grade oils, the kinematic viscosity is measured at a temperature of 100 °C (212 °F) in units of mm2/s (millimeter squared per second) or the equivalent older non-SI units, centistokes (abbreviated cSt). Based on the range of viscosity the oil falls in at that temperature, the oil is graded as SAE viscosity grade 20, 30, 40, 50, or 60."

In the chart above, the oil meets the winter rating and then VII - viscosity index improvers - are added to artificially thicken the oil. They are not durable, do not lubricate, and for oils with a wide viscosity spread (5w-40, e.g.), can be a large part of the oil by weight and volume.

if you take good look a the values above, you can see that unless you routinely start your engine with the engine room below freezing, you are wasting valuable lubrication capability by not running straight-weight oil. You are also gaining no "cold start" benefits.

Nomad Willy asked above about VII's being rubber. In the past, they were. A petroleum engineer explained to a group of us that in fact, in the 80s, they actually recycled tennis shoe soles by grinding them to fine dust and adding them to oil. Nowadays, they are far more highly engineered synthetic molecules, but still the same principal.



This is pretty engine-specific. How hot the oil runs on average and in unique spots, how much shear is experienced in different sections of the engine (internal gears, etc.), total oil volume, presence or not of a turbo, etc. all effect this. Some engines are really easy on oil, and others can chew up the VIIs in short order because of design characteristics.

Gas engines I know better; so let me give an example there - there are gas engines on the road that will destroy an average 5w-30 motor oil in 5 to 6k miles. The same engines can run happily 10k miles on higher quality 10w-30 synthetic (Yes I'm looking at you, Toyota 1mz-fe V6).

I would encourage everyone following this thread to read the Wiki article. For me, it explained everything. I think it will answer everyone's questions and clear up any and all fallacies rendered in this thread. It will also give pause to some with specific engines. Take heed. Here is an example, not a diesle and not in a boat but very interesting, at least to me, and a good reason why this article should be read.


Just last week my brother-in-law told me a car dealer story that I though was pure bull. He owns a Chrysler Pacifica that developed a low oil pressure problem. The dealer asked whether he had changed the oil. He had. Dealer said that was the problem, that the likely cause of the low pressure was a worn oil pump or position sensor, that he should be using only dealer-supplied oil. I called bull, that any oil that meets the SAE spec for that engine is okay. WRONG. Here is what the article said.



Most engines built before 1985 have the flat/cleave bearing style systems of construction, which is sensitive to reducing zinc and phosphorus. For example, in API SG rated oils, this was at the 1200–1300 ppm level for zinc and phosphorus, where the current SM is under 600 ppm. This reduction in anti-wear chemicals in oil has caused premature failures of camshafts and other high pressure bearings in many older automobiles and has been blamed for premature failure of the oil pump drive/cam position sensor gear that is meshed with camshaft gear in some modern engines.


Who would have thunk? I guess dealers are not always telling stories.


The article also contains a good discussion on synthetics. Read that section and take from it what you will. I think it may change some minds. here is an example.



Synthetic oils are derived from either Group III, Group IV, or some Group V bases. Synthetics include classes of lubricants like synthetic esters (Group V) as well as "others" like GTL (methane gas-to-liquid) (Group III +) and polyalpha-olefins (Group IV). Higher purity and therefore better property control theoretically means synthetic oil has better mechanical properties at extremes of high and low temperatures. The molecules are made large and "soft" enough to retain good viscosity at higher temperatures, yet branched molecular structures interfere with solidification and therefore allow flow at lower temperatures. Thus, although the viscosity still decreases as temperature increases, these synthetic motor oils have a higher viscosity index over the traditional petroleum base. Their specially designed properties allow a wider temperature range at higher and lower temperatures and often include a lower pour point. With their improved viscosity index, synthetic oils need lower levels of viscosity index improvers, which are the oil components most vulnerable to thermal and mechanical degradation as the oil ages, and thus they do not degrade as quickly as traditional motor oils. However, they still fill up with particulate matter, although the matter better suspends within the oil,[citation needed] and the oil filter still fills and clogs up over time. So periodic oil and filter changes should still be done with synthetic oil, but some synthetic oil suppliers suggest that the intervals between oil changes can be longer, sometimes as long as 16,000–24,000 kilometres (9,900–14,900 mi) primarily due to reduced degradation by oxidation.



By the way, oxidation is what causes soot formation.
__________________

catalinajack is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 05:04 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×