Export thread

bertsmobile1 said:

Hydros work because the pressure from the viscious friction applied to the oil as it escapes from the space between the valve chest & the valve plate is greater than the pressure needed to move the pistons.
It is an astoundingly complicated set of equations and has taken decades to get right and you think that you can just splosh in an oil with substantially different characteristics just because it is currently fashionable for those with no understanding about oils to put a synthetic oil in everything ?
The only thing that is "safe" to do with hydro oil is to go to a thicker oil to compensate for wear between the valve chest & valve plate and that only works 1 time in 10 and even then is only short term.

Click to expand...

hlw49 said:

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.

Click to expand...

bertsmobile1 said:

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.

Click to expand...

hlw49 said:

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.

Click to expand...

bertsmobile1 said:

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 .

Click to expand...

Fish said:

I think that Dixie Chopper used Lucas oil in everything back then.

Click to expand...

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.​

Lubricant Flow Rate - an overview | ScienceDirect Topics

www.sciencedirect.com

SAGE Journals: Your gateway to world-class research journals

Subscription and open access journals from SAGE Publishing, the world's leading independent academic publisher.

journals.sagepub.com

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

hlw49 said:

Yes they did and still do but it was his choice.

Click to expand...

bertsmobile1 said:

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.​

Lubricant Flow Rate - an overview | ScienceDirect Topics

www.sciencedirect.com

SAGE Journals: Your gateway to world-class research journals

Subscription and open access journals from SAGE Publishing, the world's leading independent academic publisher.

journals.sagepub.com

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

Click to expand...

350Rocket said:

Y

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.

Click to expand...

bertsmobile1 said:

IF you don't understand the basics then all you can do is put blind faith that what some one else has said is factually correct .
As you are totally unwilling to put in the work to educate yourself then you will never actually understand how lubrication works.
I started my learning curve back in 1972 in the final years of my degree with a 2 hour lecture once a week for 13 weeks.
So that is 26 hours of face to face lectures + 13 more of tutorials + 13 more of practicals + 51 of pre lecture back ground reading before lectures.
How many hours have you spent on face book ?
As for mower engine as was previously stated is all using a synthetic or semi synthetic will do is cost you more money .
But if it makes you feel good then do it all it will do is waste your money .
While their history goes back decades fully synthetic oils were developed commercially for F1 racing where spending $ 1000 / gallon on oil is petty cash.
The engines in F 1 are pushed to their max they run at a lot higher temperatures than you mower ever will and every part has been cut down to the absolute minimum weight that will hopefully stay together for the length of a race and the manufacturing tollerances are substantially tighter than your mower ever will plus the oil plays a massive part in cooling the engine , or rather keeping the internals at a constant temperature , again totally irrelevent to an ir cooled mower engine and requires a bit of maths .
Viscious friction robs power from the tailshaft so anything that can reduce it is a big + in racing.
When we raced speedway all of the engines run total loss oiling and you do notice the difference in responce between that and the same engine mounted into a Hagon frame with an oil tank for short circuit
Synthetic oils they stayed as an exotic item even during the oil crisis of the 70's when I was in college . untill California tightened emission laws then all the major engine makers found that the thinner oils allowed the engine to crank faster so the first cylinder to do a full induction cycle fired reducing the unburned fuel passed out the tail pipe thus meet the starting emissions tests for almost no developement costs.
The engines were run to destruction & oil galleries modified where necessary.
The oil companies were then told we want engine oils with these properties of the fully synthetic oils for our production engines but we will only pay $X / gallon for them .
Thus the semi-synthetic ( and that name is total BS as the oil is not synthetic & never was ) oil was born by stripping the dreaded "Dino oil" into some componant parts then recombining them in proportions that would not normally happen and that is part & parcel of the normal processing of normal oils .
All that the oil companies did was add a couple of extra distillation processes to the regular processing .
True synthetic oil, created by reacting gasses together under pressure is a different animal but you won't find it at your local discount car parts shop.

The oil companies then had a premium product that cost marginally more than the standard product but because of the hype around it could be sold for 3 times the price of regular oil and pushed it hard by extolling its better properties, most of which was almost true but none of it of any real benefit for any engine not specifically designed to run it .
So you can run it for 3 times as long as you can run standard oil before it oxadises and starts to brake down chemically.
But that is not why you change your oil
You change it to remove the acid byproducts of combustion which happen regardless of the oil used and more importantly to remove the ultra fine particulates that errode your engine the exact same was as the Colorado river has erroded the Grand Canyon , but they fail to tell you that.

As for mower engine what can I say?
Probably once or twice a year an old worn out 2.5Hp side valve B & S powered mower comes into the shop with about 1/3 of the original oil still in the crankcase burned to the consistency of triple cream on a mower that the owner has had since the 80's and never so much as checked to oil let alone change it or even top it up.

And I would imagine every tech on here would have the same thing happen to them every year
Your 1981 B & S engine will run happily of full splash lubrication and there is a good chance it was actually full splash .
So your use of it just goes to show your absolute failure of understanding of the fundamentials of lubrication inside an engine.
The tug-o-war between adheason, coheasion & gravity let alone the significance of valence inbalance at the terminals of the molecules, and the difference the shape of them makes to the flow of the oil through the galleries.

And FWIW the only calculations in OLDS are just barely high school level and mainly about temperature flow & heat removal .
Get yourself a copy & read it then if you have understood what was written you will have just enough information to work out weather you are being fed fact, fiction or hype.
As an old text book it is probably everywhere used for $ 5 rather than the $ 50 I had to pay when it was a brand new publication.

Over the years I have found oil to be like religion and those who most strongly argue about it do so from a position of blind faith.

On one of the motorcycle forums we ran a survey to see just how much the members understood about oil
The question was
Do multigrade oils get thicker as they get hotter. yes / no
Over 90% got it wrong .

In my TAFE classe I used to ask the question
What is the purpose of the detergent molecules in oil ?
In the 11 years I taught not s single student got the question correct
We put the same question in the final exam and agin just about every student got it wrong
They all correctly described the mechanism of how they work but the students could not get the "detergents clean" BS out of their heads that the advertising companies had implanted .
And if you are wondering.
The function of the detergent is to carry away the particulates that they encounter & prevent them from combining
Secondary purpose is to make the contaminants close to the SG of the base oil so they will circulate freely within the oil to facilitate mechanical removal .
You will find that in OLDS as well no maths required .

Click to expand...

350Rocket said:

https://bobistheoilguy.com/motor-oil-101/

Maybe this will help you out.

Click to expand...

bertsmobile1 said:

I definately do not need Bob's blogs to reinforce what I have learned from professionals , physicists , chemist , molecular engineers and taught to students , I know and if pushed could probably do some of the calculations although it has been a long time but the old texts & notes are downstairs some where .
In my undergraduate years I worked at the Defence Standards Lab , the people who invented X-Ray diffraction analysis of oil so you know not only what metals are in the oil, but where that metal came from so we could tell if iron for example was from a lash cap, valve stem, piston ring , cylinder sleeve , crankshaft , cam shaft , valve train gear, timing gear or any where else if we knew the actual alloys used to make the part from.
That got plotted against actual measured wear and over time it was found that you could determine engine wear from the metals in the oil thus in place of strip down & measure on aircraft engines on a hours of use basis the engine can stay untouched for a lot longer till you detect significant wear in a critical part.
This is one reason why Australia ran their helicopters for far longer than any other military service till the analysis became SOP for military equipment as $ 3000 pop is a bit much for a car owner to pay.
Dissassembling & reassembling the engines does more damage long term than using the engine .

The AA Cromotography that the interviewee was talking about is the cheap & nasty production line method because it really does not tell you what is wearing and by how much.
OTOH if you do it regularly then again sudden increases in a particular metal signifies that some thing has started to fall apart and needs to be investigated. And it should be done almost every engine change and plotted against mileage .
Way beyond the perview of mower engines
However what was originally being argued was using different oil in hydros.
The best example I can think of is the BSA B25 & B50 engines of 1970-1973.
The B 25 has a plain white metal big end so needs a lot of oil at reasonably high pressure to float the big end
The B50 has needle roller big end bearing and could just about run on crankcase fume
The B25 has a high pressure high volume oil pump
The B50 has a low volume oil pump
Racers originally fitted the B25 pump to the B50's thinking that more oil would be a benefit but what actually happened was a failures of the big end due to the roller s sliding rather than rolling
Oil passages in engines are carefully sized to get the right amount of oil at the right pressure to the place to do the required job.
Now some times it is not critical while others it is
Synthetics is early hydro drive shorten their operation life drastically
Synthetics in late models is fine and for most now days it makes little difference because they are designed that way

Click to expand...

bertsmobile1 said:

I definately do not need Bob's blogs to reinforce what I have learned from professionals , physicists , chemist , molecular engineers and taught to students , I know and if pushed could probably do some of the calculations although it has been a long time but the old texts & notes are downstairs some where .
In my undergraduate years I worked at the Defence Standards Lab , the people who invented X-Ray diffraction analysis of oil so you know not only what metals are in the oil, but where that metal came from so we could tell if iron for example was from a lash cap, valve stem, piston ring , cylinder sleeve , crankshaft , cam shaft , valve train gear, timing gear or any where else if we knew the actual alloys used to make the part from.
That got plotted against actual measured wear and over time it was found that you could determine engine wear from the metals in the oil thus in place of strip down & measure on aircraft engines on a hours of use basis the engine can stay untouched for a lot longer till you detect significant wear in a critical part.
This is one reason why Australia ran their helicopters for far longer than any other military service till the analysis became SOP for military equipment as $ 3000 pop is a bit much for a car owner to pay.
Dissassembling & reassembling the engines does more damage long term than using the engine .

The AA Cromotography that the interviewee was talking about is the cheap & nasty production line method because it really does not tell you what is wearing and by how much.
OTOH if you do it regularly then again sudden increases in a particular metal signifies that some thing has started to fall apart and needs to be investigated. And it should be done almost every engine change and plotted against mileage .
Way beyond the perview of mower engines
However what was originally being argued was using different oil in hydros.
The best example I can think of is the BSA B25 & B50 engines of 1970-1973.
The B 25 has a plain white metal big end so needs a lot of oil at reasonably high pressure to float the big end
The B50 has needle roller big end bearing and could just about run on crankcase fume
The B25 has a high pressure high volume oil pump
The B50 has a low volume oil pump
Racers originally fitted the B25 pump to the B50's thinking that more oil would be a benefit but what actually happened was a failures of the big end due to the roller s sliding rather than rolling
Oil passages in engines are carefully sized to get the right amount of oil at the right pressure to the place to do the required job.
Now some times it is not critical while others it is
Synthetics is early hydro drive shorten their operation life drastically
Synthetics in late models is fine and for most now days it makes little difference because they are designed that way

Click to expand...

350Rocket said:

Btw, it is scary that you taught anybody on this subject.

Click to expand...

bertsmobile1 said:

All you are proving Rocket is that your understanding of the physics & chemistry of oil is not as good as you think it is
Multi grades get thinner as they get hot
I said that and your GURU said that
it is just multigrades thin at a slower rate so an oil that was 10 at room temp is equivalent to one that was 30 at room temp when they are both at operating temperature
Detergents carry away what surficants & solvent dislodge
Dispersants cause the detergent wrapped particulate to do what their name suggest disperse and not agglomerate ( detergents do the same things but to a lesser degree )
An oil that is labeled ad "detergent" may or may not also have surficants & solvents in it
Flow charasteritisc are determined by the same factors regardless of weather the force creating the flow is gravity or a pump all that changes is the pressure
With all things being equal the volume of oil that can pass through a specific hole will be greater for synthetics because of their reduced internal friction
Thus at each and every bleed off point more synthetic oil will flow through the holes and into the sump than a conventional oil will
SO an engine designed to run synthetic oils will usually have smaller holes
The crunch comes where there is just not enough oil at sufficient pressure at then end of the line to maintain a complete film .
It is not really rocket science.

Now to get back to the actual question which was about hydro transmissions
synthetics will flow at a higher rate through the gap between the valve chest and the valve plate as there is NO SEAL so the system is relying on the resistance of the oil escaping between the two surfaces being higher than the resistance of the motor pistons , which is why they have to run a full speed all the time
To control this the surfaces of the valve chest & valve plate are machined to a specific surface roughness to create a high resistance turbulent flow situation when used with an oil of specific flow rate ( or slower )
Synthetics are specifically to flow fast so when used in hydros designed to run on standard oils will fail prematurely.
I did try to work out what you were saying in those screen shots but they were very difficult to follow as to what was you & what was me which makes it too hard to follow your lines of arguement.
FWIW I was trained in applied sciences so I am always more than happy top be proven wrong so I can update to the latest most correct information
Our understanding of things is always getting deeper & deeper but the opperative word is proven.
I have spent too mush time calculating flow rates through pipes ( furnace flues and metal through moulds mostly ) to accept things that counteract what I know is applicable .

I do conceede that some of my wording could have been better but I was not trying to write another Phd thesis with footnotes & annotations, just some thing that most could be able to visualize without going back & doing 20 rewrites and full of jargon to make me sound smart that many will not understand thus find confusing .

Click to expand...

clubairth said:

I use Mobil 1 Synthetic 15W-50 as called for in the manual. Those Hydro's do run very hot and I was surprised to see it gets so hot that it turns the Mobil 1 black from the heat!
.
.
.

Click to expand...

slomo said:

That is rubber hose bits flaking off getting into the oil. If heat was to do as you describe, that oil would be over 400F+. Which is hotter than any oil can stand and not deteriorate.

Click to expand...

If Your Engine Oil Turns Black, Don't Panic

Engine oil turns black for a few reasons, including time and additives. Here's how to tell when it's time for a change.

knowhow.napaonline.com

Jcook78 said:

The manual says “Fill with SAE 20W50 motor oil, 15W50 synthetic oil or 20W50 synthetic oil (Hustler® Full Synthetic 20W50 Hydrostatic Transmission Oil is recommended).” I used a synthetic on my last mower, may do it again on this one when it’s due. Depends on what mood I’m in that day. I’m a journeyman hydraulic mechanic for the Dept of Defense..I say use whatever makes you feel better.

Click to expand...

slomo said:

For the little I know about oils, I'd have to agree with Bert on everything he said.

350 Rocket's third party source is commenting on "some" similar things Bert is saying but attempting to say them in a far different way. Like the classic, that letter or number on the bottle is how fast that oil can get back up to the pump pickup screen?? WHAT?? Non of this third sources info is anything new or close to ground breaking about oil. Dude is a parrot.

Click to expand...

mehan said:

I agree: follow the manual. I would not trust an engine oil in this application. Viscosity may be OK but engine oil has a lot of additives which may not help in this application. Stick with transmission fluid of the recommended viscosity.

Click to expand...

bertsmobile1 said:

What was being originally said is the best oil is what the item was designed to run on and not some new beaut formulation because it says so on the bottle.
Some times using a higher grade of oil will be beneficial, some times it will make no difference whatsoever and some times it will be detrimental .
Fluids, all fluids be they water oil or even honey follow the rules of fluid dynamics with relation to flow
and all fluids have a resistance to flow
The simple example we are all familiar with is water through a hose and the pressure loss over distance.
Run a a hose , no nozel on the end for a few minutes and see how far the water goes strait up
Then hook 2 together and do the same , then 3 if you have one and even four
The longer the hose the lower the flow rate despite the original pressure ( call it an oil pump ) remains the same and around here it is 80 psi
The lower rate of discharge is because of the internal friction of the water molecules caused by the ones nearest the wall of the hose suffering turbulant flow .
If the internal friction is lower this effect is less pronounced so more water will flow through the same space per unit of time .
And this effect is the same for any fluid from water through to bitumen and also powders if they are ground fine enough like flour or cement.

Because the molecule sizes in synthetic or even semi synthetics is both smaller and more consistant then they flow faster under pressure in confined spaces and in particular when being pressurised or forced through a constricted space
Inside your hydro the only reason it moves is because the resistance of the oil to flowing between the rotating cylinder block and the stationary kidney plate is higher than the resistance from the piston pushing the swash plate.
So when designed to run on synthetics the space between these two surfaces must be either closer or rougher.
And there is no seal between the pistons and the cylinders they run in either so again the resistance of the oil to flow around the side of the piston is all that is making a seal and preventing all of the oil flowing around the piston rather than make the piston move.
Most of the heat heat energy that is converted from the mechanical energy is derrived from this internal resistance to flow

I hope this is clearer than the previous that was written off the top of ones head

What is written on the web should always be taken at face value because I could be a retired 70 year old graduate with multiple degrees & diplomas who worked all his life in the oil industry ( and I am not ) or a 10 year old with advanced internet search skills who gets their jollies by pretending to be the above and fooling people or any where in between .
So Rocket is more than welcome to cross post everything written in order to validate what was posted with other electrons in cyber space that he believes in .
The fact that he felt compelled to cross post tells me either I failed to properly express myself (and yes it could have been better ) or he does not have sufficient understanding to evaluate it himself so sought the council of others whom he has faith in

Knowledge is some thing that is acquired over time and never from a single identifiable source and relying on any single source that can not be verrified as a primary source is always fraught with dangers as every step away from the primary source you get the facts get closer to opinion.
But to verrify you need to understand the basic principles be that mathematically or practically and with oils it is all about the molecules , the size shape distribution and valencies and the way they interact with each other & the materials they come in contact with

Click to expand...

350Rocket said:

Just looking up the oil capacity for my snowblower and noticed on the maintenance tips tag.... viscosity is not even mentioned. The most important thing it says is "synthetic is recommended below 32f" which is what the conditions will be basically all winter.

Click to expand...

350Rocket said:

Yes knowledge comes from years of experience or reading. I'm not claiming to be an expert but years of reading various sources (mostly bobistheoilguy as it is actually run by a chemical engineer of some kind and has a great FAQ section) I wanted to make sure I wasn't going crazy since almost everything you said went against everything I had ever read except for myths from old farmers or mechanics. I tried my best, and double checked my sources of information, but I can't make you do the same.

Click to expand...

bertsmobile1 said:

Well Rocket,
I had bit of spare time today as the phone is down so no phone calls.
I re-read this whole thread and even your go-to Bob, chapters 1 through to 6
Nothing there that is any different to anything I posted other than the words we used to say it . "Use what is recommended by the makers & replacing a std oil with a synthetic MAY do nothing other than cost more money"
I really think you have the idea that I am anti-synthetic and thus read what I post in a highly subjective mannar.
Add to that being in OZ what gets written is as I would do for an Aust reader, we do not have NASCAR down here ( seemed to bother one of the cross posters ), but when Mobil was trying to convince everyone to buy their much more expensive synthetic oil they pushed the F1 heritage very hard so that is what comes to mind first.
So perhaps you would find "the existing synthetic oils from avaition were modified to meet the demand situations of motor racing where standard oils were found wanting and money was not a problem " more pallitable to your USA thinking.
Other that that then you are welcome to consider me as a synthetic hating blithering idiot.
But try and find the answer to "why does the oil remain between the slipper bearing and the journal on a big end and not get totally pushed out at BDC on the power stroke " .
Go to some of the piston ring makers web pages ( total seal is good ) and read about how a piston ring actually works and then go back to your trusted informers and ask them to explain " why the oil stays behind the ring and not just get pushed out "
And for mower specific applications
"why does oil flow between the con rod & journal on a full splash engine when gravity and momential inertia should have it all tossed away and not flow between the very close spaces "
And ask those whose opinion your trust
"why does the oil in a hydro drive push the pistons and not all escape down the sides of the pistons ( remember there are no piston rings to make a seal ) or between the cylinder block and kidney plate where there is no seal either "
And FWIW there is nothing stopping the oil going directly from the inlet to the outlet holes in the kidney plate either as previously mentioned one plate 2 to 6 slots with oil coming in one slot under pressure and going out the other with no back pressure to prevent the flow which is how most hydros fail.
Troll through the posts here and you will find lots of photos of failed kidney plates.

And I was a member of the ASTM from 1972 through to 1994 as I had to be able to certify goods destined for the USA market and the USA would not accept the Aus NATA certification.

Click to expand...

enigma-2 said:

An engineer at Briggs told me that conventional oil is needed during break in to seat the rings properly. .

Click to expand...

MParr said:

I’m pretty much in agreement. A hydrostatic transmission is not and engine. Therefore, it really doesn’t matter whether you use a synthetic oil, blend or conventional oil in the hydros. A 20W50 conventional oil with high ZDDP content is probably going to be the best bang for the buck. Most of those oils will be geared for classic cars or racing engines. Why? Because, some 20W50 oils have the ZDDP and Phosphorus content lowered to prevent the cooking of catalytic converters in cars.
Mobil 1 15W50 is high in ZDDP and Phosphorus. Valvoline VR1 20W50 is a really good choice and is much cheaper than Mobile 1 15W50.

Click to expand...

350Rocket said:

Oh and here is another chart just like most engine manufacturers have in their owners manual... proving that viscosity is not as critical as most think.

Click to expand...