Standard vs Synthetic Oil in differential

350Rocket

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Tell that to a friend of mine that has a 1998 Dixie Chopper with a Kohler cv25 that has about 9,000 hours on it running Mobil 1 Synthetic oil in. I'm sure Kohler never recommended synthetic oil back in those days.
My 1976 Oldsmobile 350 V8 never recommended synthetic oil but I've run nothing but since 2007 for the last 110k miles. Total mileage is probably we'll over 300k miles.
Who knows whether it makes a 2% or 20% increase in lifespan but if you're not planning on replacing the vehicle for 40+ years why not buy the better oil if it's available on sale for the same regular price as conventional?
As far as lawn equipment, people (myself not included) tend to leave maintenance way longer than they should and synthetic will hold up better in those cases.
The hydro in my cub cadet has to be removed to change the fluid so you can bet when I get around to doing it that I will be using full synthetic 20w50 or 15w50 (both recommended fluids for it) because I can't just dump it every couple years.
 

bertsmobile1

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And I have a 1926 BSA B2 that I have done about 125,000 miles on using SAE 30 mower oil and BSA never specified mower oil
The landlord had a set of 2000 series Cub Cadets that we mow the orchard & paddocks with to the tune of around 300 hrs each per year and they run SAE 30 in the Kohlers as well .
The oil that goes in is nowhere as important as how often it comes out .
We had a club member with a 1966 A65 that would not hold pressure at idle when hot when he bought it.
He did 180,000 km on that engine running Valvoline 20W50 and sold the bike 20 years latter with the same worn timing side bush as it had when he bought the bike .
And BSA recommended a bottom end strip & rebuild every 30,000 miles , Rhett never touched his apart from changing the oil at the end of every run .

So you point, is pointless

No such thing as a super oil that will make an engine run forever .

I had a fleet of L300's all of which went for more than 1,000,000 Km without a bottom end failure and they were run on reprocessed 20W50 strait oil and these were all LPG powered so supposed to run LPG rated oil.

Mower engines are trash , the bulk rely on splash apart from the big end for lubrication so the oil used makes little difference.
Now the XJ650 & XJ750 we used to run ( 12 at one time ) all have metering jets on each cam & crank journal and all of them are different sizes because oil pressure & volumes at each journal is citical and carefully calibrated , running a thinner base oil in them would be a disaster.

Then we come to Hydros
If you have ever pulled one down you would see there is no seal whatsoever between the cylinder body & the valve plate.
The hydro companies machine these to a specific roughness so the resistance to the oil leaking is higher than the resistance of the oil pushing they pistons .
There the wrong oil, and in particular using a synthetic with a lower specific viscosity will cause premature failure .
And the opposite will also happen as with a slower flowing standard oil there will be insufficient flow to float the surfaces.
 

350Rocket

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And I have a 1926 BSA B2 that I have done about 125,000 miles on using SAE 30 mower oil and BSA never specified mower oil
The landlord had a set of 2000 series Cub Cadets that we mow the orchard & paddocks with to the tune of around 300 hrs each per year and they run SAE 30 in the Kohlers as well .
The oil that goes in is nowhere as important as how often it comes out .
We had a club member with a 1966 A65 that would not hold pressure at idle when hot when he bought it.
He did 180,000 km on that engine running Valvoline 20W50 and sold the bike 20 years latter with the same worn timing side bush as it had when he bought the bike .
And BSA recommended a bottom end strip & rebuild every 30,000 miles , Rhett never touched his apart from changing the oil at the end of every run .

So you point, is pointless

No such thing as a super oil that will make an engine run forever .

I had a fleet of L300's all of which went for more than 1,000,000 Km without a bottom end failure and they were run on reprocessed 20W50 strait oil and these were all LPG powered so supposed to run LPG rated oil.

Mower engines are trash , the bulk rely on splash apart from the big end for lubrication so the oil used makes little difference.
Now the XJ650 & XJ750 we used to run ( 12 at one time ) all have metering jets on each cam & crank journal and all of them are different sizes because oil pressure & volumes at each journal is citical and carefully calibrated , running a thinner base oil in them would be a disaster.

Then we come to Hydros
If you have ever pulled one down you would see there is no seal whatsoever between the cylinder body & the valve plate.
The hydro companies machine these to a specific roughness so the resistance to the oil leaking is higher than the resistance of the oil pushing they pistons .
There the wrong oil, and in particular using a synthetic with a lower specific viscosity will cause premature failure .
And the opposite will also happen as with a slower flowing standard oil there will be insufficient flow to float the surfaces.
I understand there is a difference with hydros and I have no experience with them other than seeing that both synthetic 15w50 and conventional 20w50 are recommended for mine.
And once again you put words in my mouth...I never said it was a miracle product, I said we don't know if it increases lifespan by 2% or 20% but either way it does and I'm not looking forward to pulling the engine on either my 38 year old Oldsmobile or my 9400 hour 2005 Silverado. So my point is not pointless. I just said I personally prefer to use the better product. Families vehicles I usually just use conventional because I know they won't keep it long enough to matter, but that's not the point.
Also the base oil is not thinner on synthetic oil, various oils have different base oil viscosities so it depends on the specific oil and not whether it is synthetic or not. Like I said before you need to do some research before spreading myths.
 

bertsmobile1

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What people fail to appreciate is engines are designed for a specific type of oil .
That includes the size of oil holes so that the right amount of oil will flow through them to do the job required and there will be sufficinet oil pressure left in the system to lubricate parts further down stream of the oil pump.
They also fail to understand that the flow charasterisc of oil under pressure is totally different to oil flow under gravity which is how the numbers on the front of the bottle are measured.
So all that the numbers on the bottle actually tell you is how the oil will drain back down the drain holes to the sump .
So for instance a synthetic oil that flows faster & easier will not provide enough oil to the last 2 journals on a strait 8 engine because all of the pressure will bleed off lubricating the first 6 cylinders .
Assuming cylinder 1 is closest to the oil pump, the slippers on it will have little rivers all through them because it got too much oil by volume because to use the synthetic oil the oil holes in the crankshaft need to be smaller because the oil flows freer .
It takes years for very experienced engineers to design & test the lubrication system in anything to ensure it all works properly with the lubricant it was designed t & tested with.
Then Joe Idiot comes along and thinks just because some race driver, big brested bimbo, whoever pops up on TV and says this stuff is better it will automatically make whatever they put it in run forever .'
Some times it might make no difference and some times it will
If it makes no difference then the user is pouring money down a hole & wasting the planets resources
If it does make a difference then that door swings both ways
Some times it will be better but most times it will be worse.
However Joe Idiot never take responsibility for his own stupidity and will blame anything else other than him using an unsuitable lubricant .
Barnets got blasted from pillar to post because their clutch plates were slipping all over the place then after several years it was found that it was the owners shoving fully synthetic oil into their motorcycles that was causing the clutches to slip .
A similar story with NSK who copped a ton of warranty claims for excessive wear in roller big end bearings and crankshaft bearings
Same story, the freer flowing synthetics floated the rollers so they slid on the outer race rather than rolling .
This was a particularly big problem for Ducatti Desmo engines and to a lesser extent Harleys , made more confusing to Joe I Know More Than The Design Engineers , as latter models used synthetic oils so it must be OK to use it in older modles , well it was not .
 

Fish

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Tell that to a friend of mine that has a 1998 Dixie Chopper with a Kohler cv25 that has about 9,000 hours on it running Mobil 1 Synthetic oil in. I'm sure Kohler never recommended synthetic oil back in those days.
I think that Dixie Chopper used Lucas oil in everything back then.
 

350Rocket

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What people fail to appreciate is engines are designed for a specific type of oil .
That includes the size of oil holes so that the right amount of oil will flow through them to do the job required and there will be sufficinet oil pressure left in the system to lubricate parts further down stream of the oil pump.
They also fail to understand that the flow charasterisc of oil under pressure is totally different to oil flow under gravity which is how the numbers on the front of the bottle are measured.
So all that the numbers on the bottle actually tell you is how the oil will drain back down the drain holes to the sump .
So for instance a synthetic oil that flows faster & easier will not provide enough oil to the last 2 journals on a strait 8 engine because all of the pressure will bleed off lubricating the first 6 cylinders .
Assuming cylinder 1 is closest to the oil pump, the slippers on it will have little rivers all through them because it got too much oil by volume because to use the synthetic oil the oil holes in the crankshaft need to be smaller because the oil flows freer .
It takes years for very experienced engineers to design & test the lubrication system in anything to ensure it all works properly with the lubricant it was designed t & tested with.
Then Joe Idiot comes along and thinks just because some race driver, big brested bimbo, whoever pops up on TV and says this stuff is better it will automatically make whatever they put it in run forever .'
Some times it might make no difference and some times it will
If it makes no difference then the user is pouring money down a hole & wasting the planets resources
If it does make a difference then that door swings both ways
Some times it will be better but most times it will be worse.
However Joe Idiot never take responsibility for his own stupidity and will blame anything else other than him using an unsuitable lubricant .
Barnets got blasted from pillar to post because their clutch plates were slipping all over the place then after several years it was found that it was the owners shoving fully synthetic oil into their motorcycles that was causing the clutches to slip .
A similar story with NSK who copped a ton of warranty claims for excessive wear in roller big end bearings and crankshaft bearings
Same story, the freer flowing synthetics floated the rollers so they slid on the outer race rather than rolling .
This was a particularly big problem for Ducatti Desmo engines and to a lesser extent Harleys , made more confusing to Joe I Know More Than The Design Engineers , as latter models used synthetic oils so it must be OK to use it in older modles , well it was not .
Can you share any sources for information about these examples? I have done a lot of research on oil over the last 20 years (just out of interest) and I've never heard of anything like this. And I've certainly never read that it flows freer.
 

bertsmobile1

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So how much do you know about Fluid Dynamics ?
Are you familiar with the Navier – Stokes equation or Poiseuille's law for viscous flow ?
If you want a single source that will contain every thing I have learned over the past 50 Years, then I am yet to write my memoirs .
People tend to take the lazy approach & expect to understand the nature of oil flow without any understanding of the bulk mechanics or chemistry liquids, let alone oils .
Now the first text book I had to read & understand was Lubricants Cutting Fluids & Coolants by WF Olds back in the early 70's, a good place to start
The Chemisrty and Physics of Petrolium Liquids ( translatttion from Russian ) was the next text I had to adsorb.
Post graduation hundreds of trade papers & journal articles to keep current particularly as some of the trad school students were a lot more familiar than I was
Then there were 3 or 4 conferences I managed to con the boss into allowing me to attend , but most of those papers are long lost .

The last thing I read on the subject which was reasonably accessable was a couple of years back when I was having a discussion about synthetic oils on a different forum.


Most of the useful information will be found in industry && research journals as an individual paper with a very specific title .
using search terms like c=synthetic vs standard oil will get you nothing of any value and 99% opinion or advertising BS
 
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350Rocket

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Y
So how much do you know about Fluid Dynamics ?
Are you familiar with the Navier – Stokes equation or Poiseuille's law for viscous flow ?
If you want a single source that will contain every thing I have learned over the past 50 Years, then I am yet to write my memoirs .
People tend to take the lazy approach & expect to understand the nature of oil flow without any understanding of the bulk mechanics or chemistry liquids, let alone oils .
Now the first text book I had to read & understand was Lubricants Cutting Fluids & Coolants by WF Olds back in the early 70's, a good place to start
The Chemisrty and Physics of Petrolium Liquids ( translatttion from Russian ) was the next text I had to adsorb.
Post graduation hundreds of trade papers & journal articles to keep current particularly as some of the trad school students were a lot more familiar than I was
Then there were 3 or 4 conferences I managed to con the boss into allowing me to attend , but most of those papers are long lost .

The last thing I read on the subject which was reasonably accessable was a couple of years back when I was having a discussion about synthetic oils on a different forum.


Most of the useful information will be found in industry && research journals as an individual paper with a very specific title .
using search terms like c=synthetic vs standard oil will get you nothing of any value and 99% opinion or advertising BS
It looks like you're just sending me on another wild goose chase, reading a bunch of math equations that have nothing to do with what difference there is between a conventional group 2 oil or a group 3 oil or Pao or ester oils. I'm no chemist or anything but there are several physicists/formulator/tribologists that have put this into layman's terms for us......lots of information out their dispelling myths about synthetic oil and nothing I can find that backs what you're saying.
I should have blown up my old 1981 3hp Briggs mowing down steep embankments with full synthetic Pao oil in it when I was doing it as a side job many hours a week, if what you're claiming is true.
I can see we're never going to agree on this and you're just going to throw a bunch of fluid dynamics math equations at me that don't do anything to back your statements.
 
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