Synthetic oil bad in a lawnmower? Any truth in this self proclaimed experts statements?

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I was starting the mud motor on my boat the other day (212 predator engine 6.5hp) in 24 degree temperatures. Sure was glad I had switched it to synthetic oil, it was hard enough to pull over with the stiff grease in the drive shaft. Low temps and high temps are where synthetic oil shines but you notice it way more in low temps.
 

350Rocket

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It isn’t break in but the manual has some specific advice about change intervals.

I’ve come to like the Honda oil for no others real reason than it’s the right amount and you don’t end up with partial quarts sitting around .
I kept the bottle for my champion generator because it's like 1.2L or something (exact refill for the generator). I used the supplied oil for 3 hours of break in the changed it with Pennzoil platinum 5w30 but I will always transfer the oil into the original oil bottle for exact refill.
 
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I was starting the mud motor on my boat the other day (212 predator engine 6.5hp) in 24 degree temperatures. Sure was glad I had switched it to synthetic oil, it was hard enough to pull over with the stiff grease in the drive shaft. Low temps and high temps are where synthetic oil shines but you notice it way more in low temps.
What winter rating the oil holds is agnostic to the base stock composition. Either it meets the requirements for the rating or it doesn’t. Yes it’s true that a conventional oil won’t meet the requirements for a 0W rating but I doubt you’re starting your boat at -35.
 

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I was starting the mud motor on my boat the other day (212 predator engine 6.5hp) in 24 degree temperatures. Sure was glad I had switched it to synthetic oil, it was hard enough to pull over with the stiff grease in the drive shaft. Low temps and high temps are where synthetic oil shines but you notice it way more in low temps.
Pull start motors is where I can tell the difference in 15W and 0W - even in Texas winters. Figure it’s easier on small batteries like my lawn tractor too - so swapping in 0W40 for winter …
 
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I live in a pretty extreme environment, unfortunately I do have to start small engines in sub-zero (-35f is not uncommon) temps on occasion, usually in an emergency like starting generators during a power outage in blizzards ect... It’s actually pretty serious business because there’s no one to come save you and if you lose power for too long you freeze up in pretty short order. So I use light synthetics and have back ups to back ups. I also keep a small quantity of fuel in a warmer location so it will atomize better and actually start.
 
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I'm sure it is my B&S has only lasted 18 years on it. That is where I get rid of all my left over top off oil. That Briggs is likely to implode any moment even though it isn't running!
 
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I was changing the oil in my JD 425 a while back and my neighbor, who worked for Auto Zone a while back, came along and noticed I was putting in synthetic oil, and he proceeded to ask/tell me I could never go back to dino oil. . . Just complete ignorance on the subject, plain and simple.

ANYONE who believes that the difference between syn/dino oil is a deciding factor in oil suitability has not been away for the last 30 years or more. I could go into the different reasons in which this makes no sense, I'll just say one thing, an awful lot of supposedly dino oils need syn added to make grade, one example is 0W20.
I've used both oils in cars, mowers, all forms of L&G equipment and switched back and forth for years and years and never a problem.
 
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"That includes the size of oil holes so that the right amount of oil will flow through them to do the job required"

If the proper viscosity of synthetic oil is used, then no worries there.
 
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I have used 20 or 30 grade automotive oils in my big air compressors in the garage for decades. I think they recommend non detergent oils so there is no foaming but these days what good oil foams anyway. And think of the build up resulting from a non detergent oil. It cannot be good for anything.

Same oils in all my yard equipment as well.

Ali
 
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Wow, that was a lot to read. In the last paragraph someone mentions teaching class and students missing questions during the semester and on the final exam. When a large percentage of students repeatedly miss questions it is usually a sign that the instructor did a poor job of covering the material. Education is about learning and not about assessing what someone has already learned. Mr. Einstein said it best when he stated that information is not knowledge. In fact, the two share very little with one another.
Lot to read? I bet nobody really read that.
 
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I had a disagreement with someone on another forum that specializes in lawn equipment/small engines about whether or not full synthetic oil is dangerous to use in a lawnmower engine. They made all kinds of statements that didn't seem right to me. I'm wondering if some of the actual professional lubrication experts on this board like Molakule or others could read some of what he's said and tell me if there is any truth in it. The only source he could give me had nothing to do with synthetic vs conventional and was the basics of fluid dynamics, which obviously I don't have experience with or time to learn at this point. All of what I learned about oil has come from this forum over the past 15-20 years of casual reading. Here are 2 posts from this guy on the thread discussing use of synthetic in a lawnmower engine:

"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 ."





"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.

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."
That sounds like something David Vizzard wrote. He has his own channel now and spends the first half and last third of every video blowing his own horn.
I thought he was a pompous ass 50 years ago, and a pompous ass now.
 
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ZeeOSix

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Here are 2 posts from this guy on the thread discussing use of synthetic in a lawnmower engine:

"What people fail to appreciate is engines are designed for a specific type of oil ."
Not one of those guys ... 😄

More like engines are designed to run on a whole range of oil viscosity, and it can even run on synthetic or conventional "type", lol.
 
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I had a disagreement with someone on another forum that specializes in lawn equipment/small engines about whether or not full synthetic oil is dangerous to use in a lawnmower engine. They made all kinds of statements that didn't seem right to me. I'm wondering if some of the actual professional lubrication experts on this board like Molakule or others could read some of what he's said and tell me if there is any truth in it. The only source he could give me had nothing to do with synthetic vs conventional and was the basics of fluid dynamics, which obviously I don't have experience with or time to learn at this point. All of what I learned about oil has come from this forum over the past 15-20 years of casual reading. Here are 2 posts from this guy on the thread discussing use of synthetic in a lawnmower engine:

"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 ."





"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.

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."
Most new riding lawn mowers recommend straight 30 with API SG-SL for a reason.
Those earlier API categories allow a lot higher levels of anti-wear additives (ex: phosophours).

API SL was the last good oil. Starting with API SM, phosphorous levels were reduced as they think it harms the catalytic converters of cars.

So if you buy a synthetic 5W-30 of your choice, it's likely to be API SP, which has much lower phosphorous levels and might cause more wear.

One possible solution: Use Castrol 5W-30 Euro A3/B4 oil (5 quart jug from Walmart or Amazon for about $28).
It has API-SL, since it needs the higher phosphorus to pass the ACEA A3/B4 anti-wear tests.
As a bonus, you get HTHS = 3.5, which is really nice if you're out in the hot sun for hours (with engine getting hot) cutting the lawn if you have a big back yard.
 
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Most new riding lawn mowers recommend straight 30 with API SG-SL for a reason.
Those earlier API categories allow a lot higher levels of anti-wear additives (ex: phosophours).

API SL was the last good oil. Starting with API SM, phosphorous levels were reduced as they think it harms the catalytic converters of cars.

So if you buy a synthetic 5W-30 of your choice, it's likely to be API SP, which has much lower phosphorous levels and might cause more wear.

One possible solution: Use Castrol 5W-30 Euro A3/B4 oil (5 quart jug from Walmart or Amazon for about $28).
It has API-SL, since it needs the higher phosphorus to pass the ACEA A3/B4 anti-wear tests.
As a bonus, you get HTHS = 3.5, which is really nice if you're out in the hot sun for hours (with engine getting hot) cutting the lawn if you have a big back yard.
Most riding lawn mowers recommend oil that meets OR EXCEEDS API SG-SL. Small engines don't need high levels of zinc and phosphorus, this is a myth. Yes, they are flat tappet engines, but the valve spring pressures are so low you can push the valves open by hand. Most of the manuals I've seen are very outdated anyway FWIW.
 
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A lot of the concern over zinc comes from guys running high performance V8s and the like with very heavy valve springs.

Even in my MG, the stock spring is something like 80lbs. I run high zinc oil mostly because I figure it’s cheap insurance for my relatively new performance cam(and cam swaps are engine out in that car) but I’ve heard a ton of stories of new cam failure in B engines that were properly broken in. There were stories of MG T-types with XPAG/XPEG engines wiping lines on new cams. That happened right around the time a lot of oils cut zinc levels, but I suspect it may have been a bad batch of cam blanks especially since it didn’t seem to happen on older cams it even reground ones.

For a small engine, zinc would be low on my list of worries.
 
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Messages
23,763
Location
Upper Midwest
Most new riding lawn mowers recommend straight 30 with API SG-SL for a reason.
Those earlier API categories allow a lot higher levels of anti-wear additives (ex: phosophours).

API SL was the last good oil. Starting with API SM, phosphorous levels were reduced as they think it harms the catalytic converters of cars.

So if you buy a synthetic 5W-30 of your choice, it's likely to be API SP, which has much lower phosphorous levels and might cause more wear.

One possible solution: Use Castrol 5W-30 Euro A3/B4 oil (5 quart jug from Walmart or Amazon for about $28).
It has API-SL, since it needs the higher phosphorus to pass the ACEA A3/B4 anti-wear tests.
As a bonus, you get HTHS = 3.5, which is really nice if you're out in the hot sun for hours (with engine getting hot) cutting the lawn if you have a big back yard.
They recommend that for superior shear resistance. So the MOFT is not too low.
 
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