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My 100CC Mountfield mower says to use either SAE30 or 10W30, but the only oil I have for it is 10W40 (for 4 stroke garden machinery)...

Would that be alright to use ?

Probably fine, but I'll let the 'pros' confirm since I'm new here.

General rule about oil: The greater the difference between the two weights (in this case, 10 and 40), the less 'sheer resistance' the oil has. In other words, properties of the oil can break down faster. I'm not sure if this is an issue with these motors, but something to be aware of. If you do go with that large of a difference, see if you can get a synthetic. Greater sheer strength.

My mowers call for 10-30 but all I have ever used since new 26 years ago is 15-40 Rotella since it is a heavy duty truck oil and they don't have catalytic converters so Rotella has more ZDDP for greater engine protection.
Since your mower don't have a cat this oil would be ideal for it also.
Air cooled engines run very hot in the summer the 15-40 just gives a little more protection but I always allow mine to warm up before throwing against the Governor this lets the oil thin out some before putting it to work.

A few weeks ago I bought a new John Deere and the manual said use 10-30 or 15-40 care to guess what I'm going to use in it.:laughing:

yoster said:

Probably fine, but I'll let the 'pros' confirm since I'm new here.

General rule about oil: The greater the difference between the two weights (in this case, 10 and 40), the less 'sheer resistance' the oil has. In other words, properties of the oil can break down faster. I'm not sure if this is an issue with these motors, but something to be aware of. If you do go with that large of a difference, see if you can get a synthetic. Greater sheer strength.

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Not true. I don't know exactly what you mean by "shear resistance" (or did you really mean to say "sheer resistance"?) but with multigrade oil, the higher number represents the viscosity at operating temperature, while the lower number is the viscosity at cold cranking temperature, something only of interest when starting a snowblower.

Be that as it may, to achieve the wider viscosity range, the oil either has to be synthetic or have more additives. It's probably distrust of all the additives that has given multigrade oil a bad name. Anyway, if you really want to read debates about oil, go to - Bob is the Oil Guy and read the forums. Lawnmowers are a relatively low stress, slow speed application and any motor oil will do, within reason. I remember once reading somewhere that 50-weight oil was the best for Briggs & Stratton engines, so I tried it. It worked just fine, but was a bitch to pull-start in the late fall when it was starting to get cold.

oldyellr said:

Not true. I don't know exactly what you mean by "shear resistance" (or did you really mean to say "sheer resistance"?) but with multigrade oil, the higher number represents the viscosity at operating temperature, while the lower number is the viscosity at cold cranking temperature, something only of interest when starting a snowblower.

Be that as it may, to achieve the wider viscosity range, the oil either has to be synthetic or have more additives. It's probably distrust of all the additives that has given multigrade oil a bad name. Anyway, if you really want to read debates about oil, go to - Bob is the Oil Guy and read the forums. Lawnmowers are a relatively low stress, slow speed application and any motor oil will do, within reason. I remember once reading somewhere that 50-weight oil was the best for Briggs & Stratton engines, so I tried it. It worked just fine, but was a bitch to pull-start in the late fall when it was starting to get cold.

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Gotta love a post that starts with 'not true.' Well, I don't want to start some big oil discussion, but if you want to know more you can read for yourself at many oil forums, or bob is the oil guy, etc. I'm not talking about what the lower and higher numbers mean, in fact that's not all what I said, I'm referring to the breaks between the numbers and what impact that can have (outside of what the numbers themselves mean). And yes I meant shear resistance.

Did a quick google search on the topic, you can read for yourself here:
Motor Oil Viscosity Grades Explained in Layman's Terms
Scroll down to "Drawbacks of Viscosity Improving additives" - basically, the larger break between the two weights, the more additives required. Take that in conjunction with the information in that URL and you'll see what I'm getting at.

So basically 10W40 is fine!

My engine doesn't have a throttle, however I will let it warm up prior to putting it under any stress (I.E Mowing grass!).

I think you misread the information..

A few quotes from others that have discussed this before:

"For several years the number one recommendation of Briggs & Stratton has been synthetic 5W30 motor oil. They sell such an oil in SL formulation under their own brand name. Honda has recommended 10W30 oil in their engines for many years, with no mention of synthetic. B&S says that use of nonsynthetic multigrades in their engines might result in excessive consumption in very hot temperatures. They recommend 5W30 synthetic for temperatures from -20 to +120."

"Looking at the owners manual for my Tecumseh LV series engine, it says in their oil usage chart:

SAE 30W - For temps 32*F to 100*+F

SAE 5W-30 or SAE 10W - For temps -20*F to 40*F

SAE 0W-30 - For temps below -20*F to 40*F

Also states:

Using multigrade oil above 32*F will increase oil consumption. SAE 10W-40 is NOT recommended."

Basically, multigrade (especially 10w40 with all the additives it has..) oils are typically not recommended for air-cooled lawnmower engines. There is special multigrade 'for lawn equipment' oils out there that do NOT have these additives.. those are ok (you can tell also by looking at the oil.. it has a much lighter, almost clear color to it), though I think those are all 10-30w... not 10-40w. Single-base oils (like SAE30) also don't have these additives. Synthetic oils, while they have additives, hold up MUCH better in hotter temperatures, thus the reason why a multigrade synthetic oil is generally considered fine to use in these applications.

If anything 15-40w would be better than 10-40. 15-40 is a 2.6 factor difference.. while 10-40 is a factor of 4 (larger factor, more additives required, and a larger, negative, impact on shear strength as temperatures increase).

Of course you'll find the guy that says "I've used ____ for ___ years with no problems!" Probably true! Just want to point out the information and let you decide from there

jmurray01 said:

So basically 10W40 is fine!

My engine doesn't have a throttle, however I will let it warm up prior to putting it under any stress (I.E Mowing grass!).

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It shouldn't need warming up more than half a minute, unless it's really cold up there in Scotland (you did say elsewhere that your grass hasn't grown tall enough yet). But you're right, you don't want to put t it under load before the oil has had a chance to get to all the bearing surfaces.

And what jmurray01 indicated with the link he provided is accurate. While additives improve the viscosity index, they are what "wears out" in an oil, so it degrades with time and temperature. Synthetic oils achieve this improvement on their own, but unless it's a fetish for you, they're overkill for lawnmowers.

I don't know if this helps, but the 10W40 oil I have is almost as clear as water, so does that mean it has little additives in it and is suitable ?

I can't accurately answer that unfortunately. Unless it says it's formulated for garden equipment, I'd probably say no.

Just go down to the store and buy some regular ol' SAE30 and be done with it! $2.99 at Walmart lol!

jmurray01 said:

I don't know if this helps, but the 10W40 oil I have is almost as clear as water, so does that mean it has little additives in it and is suitable ?

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The color tells you absolutely nothing.
What brand of oil is it.
Can you buy SHELL ROTELLA where you live it is a very good HDEO in the USA more than 80 percent of the 18 wheelers on the road use it.

It is recommended by CUMMINS CAT MACK and DETROIT

The only way to check additives is with a UOA and check it for a TBN count but I can assure you ROTELLA has a great add pack including ZDDP at 1200ppm :thumbsup:

yoster said:

I can't accurately answer that unfortunately. Unless it says it's formulated for garden equipment, I'd probably say no.

Just go down to the store and buy some regular ol' SAE30 and be done with it! $2.99 at Walmart lol!

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It says "For Garden Machinery" on the bottle, so does that make it OK ?

jmurray01 said:

It says "For Garden Machinery" on the bottle, so does that make it OK ?

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Yep, that's the specification you want if you're set on using that oil. I'd still (to be formal) recommend "what your manufacturer recommends" - but between us and the fence post, you'll be fine running that.

Okay, I have to ask. How would oil "for garden machinery" differ from regular motor oil and how would motor oil not be as good?

I'd use whatever the manufacturer says so that if you have any problems during the warranty period, they won't blame you for using the wrong oil. Going against their recommendation usually voids warranties, even on totally unrelated problems.

You could lie and say you used the right oil and they probably wouldn't check, but why complicate matters over a few bucks? I realize that oil is more expensive there and extra cash is hard to come by when you're young, but I just thought I'd throw that out there.

oldyellr said:

Okay, I have to ask. How would oil "for garden machinery" differ from regular motor oil and how would motor oil not be as good?

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I need to find the article, but from what I understand, "garden machinery" oil has fewer additives (automotive oil has many additives that don't apply to these engines), or a different additive package that doesn't allow the oil properties to break down as quickly. It also mentioned that the garden oil is designed for hotter running, air cooled engines (again why synthetic can be substituted).

It's kind of like the difference between TC3 and TC-W3 two-stroke oil. The only difference between the two is that TC3 is rated for hotter air cooled engines, and TC-W3 is designed for water cooled. Running TC-W3 in an engine rated for TC3 can cause protection issues at the higher temperatures.

I'll have to probably stop at this point. I don't like posting information without the source of my knowledge, and for the life of me, I can't find that article!!! I think it was published by Craftsman.. will keep looking.. Like the other guy said though, can't go wrong with the OEM recommendation!

can i suggest ROTELLA T6...perhaps?

Well I put the 10W40 "For Garden Machinery" oil in, as I said I would, ran the mower for around 30 minutes doing the front and back lawns, and it worked fine.

No smoke, no vibrations, no misfiring, and no oil burning (I checked the dipstick once the engine had cooled).

reddragon said:

can i suggest ROTELLA T6...perhaps?

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I changed oil on my 180 JD yesterday and filled it with T6 :licking:

I can't understand why people will pay 5K for a mower then buy whatever is cheap at their local discount store for oil to put in it.

yeah!..im a believer in synthetic...one thing, besides getting the correct API rating for your machine, is the "ENERGY CONSERVING" circle label on the back..[T6 is not]..from what ive heard, E.C. is displaced easier during movement, but also is consumed [burnt] more in the cylinder

reddragon said:

yeah!..im a believer in synthetic...one thing, besides getting the correct API rating for your machine, is the "ENERGY CONSERVING" circle label on the back..[T6 is not]..from what ive heard, E.C. is displaced easier during movement, but also is consumed [burnt] more in the cylinder

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Those would be the real thin oils
My new car requires me to use 5-20 but as soon as the warranty runs out I will put a 5-30 in it.
Yes it will drop about 2 tenths of a mile per gallon but when I drive it hard the viscosity will not be like water.

I just bought a new JD Z Trak and the manual calls for 10-30 or 15-40 the 10-30 is for up to 90 degrees 15-40 is for zero to 120 degrees so the T6 5-40 is perfect. :thumbsup:

10-4..:drink:

jmurray01 said:

Well I put the 10W40 "For Garden Machinery" oil in, as I said I would, ran the mower for around 30 minutes doing the front and back lawns, and it worked fine.

No smoke, no vibrations, no misfiring, and no oil burning (I checked the dipstick once the engine had cooled).

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Great! But, to be fair, none of things you mentioned would happen regardless of what oil you used. Oil problems don't show their face until much much later.

yoster said:

Great! But, to be fair, none of things you mentioned would happen regardless of what oil you used. Oil problems don't show their face until much much later.

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Quite right. You can go too thin and away with it, but you should never go thicker than what's recommended because oil passageways are only so large and you might starve the beast. Engines are built to closer tolerances these days and 10-40 is nearly an anachronism.

Your mower can't hold more then one qt. of oil and how often do you change it once a year. Buy the best you can and use the right oil. It sure can't be a cost thing or can't you find it where you live?

Any oil along those lines is probably fine. Just make sure detergent isn't uses in the oil.

You're not likely to find any motor oil today without detergent.

Walmart carries the brand "Accell" (Accel?) - it's a non-detergent oil. Just look for ones that say on the bottle "non detergent." I know for sure it's at walmart.. so it's probably at auto stores too.

Note - Lawn and Garden oil is non detergent.. that's basically one of the factors that make it "lawn and garden"

Wow, I think we've beat this oil subject to death! LOL

oldyellr said:

You're not likely to find any motor oil today without detergent.

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I know but as a mechanic that works on these daily we order oil from rotary that doesn't have detergent.

WesternAuto said:

I know but as a mechanic that works on these daily we order oil from rotary that doesn't have detergent.

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I been running mine on high detergent oil for 26 years.
How much longer will I have to wait for my engine to vanish or whatever it is that you think will happen.

I've never had an issue with the detergent oils (Amsoil) that I've used in all of my machinery. And that's been 29 years (!) and counting.

benski said:

I've never had an issue with the detergent oils (Amsoil) that I've used in all of my machinery. And that's been 29 years (!) and counting.

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With that oil you won't have a problem.

If they had the modern day oil in the thirty's they would have used it.
Oil today is soooooo much better than in the past.

The engine manufactures now recommend a multi grade detergent oil.

The non detergent has no additives so it is thicker when cold that causes excess wear at start up and it is thiner when hot. Also NO ZDDP in non detergent.
Some people stay with what they learned years ago and never advance with the new technology.
Modern mowers use a filter to remove what is in suspension from the oil no reason to leave all that crude in the engine.

WesternAuto said:

Any oil along those lines is probably fine. Just make sure detergent isn't uses in the oil.

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Like everyone I know, I only use detergent oil in engines...
AND Non Detergent oil in older Caterpillar heavy equipment hydraulic systems....
If you use non detergent in an internal combustion engine you will eventually regret it... :smile:KennyV

yoster said:

Walmart carries the brand "Accell" (Accel?) - it's a non-detergent oil. Just look for ones that say on the bottle "non detergent." I know for sure it's at walmart.. so it's probably at auto stores too.

Note - Lawn and Garden oil is non detergent.. that's basically one of the factors that make it "lawn and garden"

Wow, I think we've beat this oil subject to death! LOL

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Okay, you experts, why would you not want detergent oil in your mower? Detergent oil cleans all the deposits in your engine and holds them in suspension until you drain it. With non-tetergent oil the inside of your engine and pistons would get coated with varnish and crud settle on the bottom of the crankcase, where it would build up and not drain easily. Or is that only for small engines without an oil filter?

Again, I really need to find that article, but from what I recall (don't quote me on this), it generally said this (basically what you said):

"If the mower has an oil filter, use a detergent oi. If it does not, use a non-detergent."

I think the idea being, you don't want junk floating around an engine if it's not being actively filtered out.

Note about the Amsoil: That oil is a synthetic, so again, all of this would not apply due to reasons previously discussed (synthetics are fine).

Here's an interesting read. It explains the situation of non-detergent often being used in lawn mowers (aka "lawn and garden" oils), but then it has the OPPOSITE stance for oil filters, recommending that you DO use detergent based oils if you don't have a filter. It doesn't say why, it just says "they can benefit."

Heck maybe it's just the case of lawn equipment using this oil type for so long that it has become the 'standard' without any real rhyme or reason.

Link:
The Difference in Detergent & Non Detergent Oil for a Lawn Mower | eHow.com

yoster said:

Here's an interesting read. It explains the situation of non-detergent often being used in lawn mowers (aka "lawn and garden" oils), but then it has the OPPOSITE stance for oil filters, recommending that you DO use detergent based oils if you don't have a filter. It doesn't say why, it just says "they can benefit."

Heck maybe it's just the case of lawn equipment using this oil type for so long that it has become the 'standard' without any real rhyme or reason.

Link:
The Difference in Detergent & Non Detergent Oil for a Lawn Mower | eHow.com

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The author of the article that you linked to actually has it backasswards.

He says with no filter use detergent but if you don't have a filter and use detergent then all the contaminates will stay suspended in the oil because you don't have a filter to remove it.

That is why some say if you don't have a filter use non detergent and leave the sludge behind in the engine.

With todays oils you would actually be better off to use a detergent oil in everything with or without a filter.

I have no idea what he is talking about when he states the number of cylinders dictates what oil you should use. I guess he thinks since it is a single cylinder then it is ok to abuse it because it is much cheaper to rebuild than a V8 :laughing:

these oil debates never fail to entertain!:laughing:

reddragon said:

these oil debates never fail to entertain!:laughing:

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Then pop some pop corn and pull up an easy chair and stick around I have a feeling this will get good.

oh yes!..with the the new metallurgy of modern engines and components ...as well as this new gas we have to deal with [remember when gas smelled good?]...its a different ballgame...some new ideas about oil need to be integrated i think :wink:

reddragon said:

oh yes!..with the the new metallurgy of modern engines and components ...as well as this new gas we have to deal with [remember when gas smelled good?]...its a different ballgame...some new ideas about oil need to be integrated i think :wink:

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I'm disappointed that this thread dyed before we even discussed HTHS # or TBN # Hmmm I wonder how many have done a UOA on what they use. :biggrin:

yeah!..we were just getting started:biggrin:

I think the reason not more interest in an oil discussion....
Those that have questions about oils have read mountains of information...
Those with little or no interest in oils... actually trust the reality that just about any modern day oil is going to be pretty good stuff.
Those that do UOA have likely switched to synthetic, and those that don't have their oil tested, most likely change oils sooner than they need...
AND a very few never change oil and they MIGHT add some, if they get an indication that something is wrong....
:smile:KennyV

KennyV said:

I think the reason not more interest in an oil discussion....
Those that have questions about oils have read mountains of information...
Those with little or no interest in oils... actually trust the reality that just about any modern day oil is going to be pretty good stuff.
Those that do UOA have likely switched to synthetic, and those that don't have their oil tested, most likely change oils sooner than they need...
AND a very few never change oil and they MIGHT add some, if they get an indication that something is wrong....
:smile:KennyV

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Yea that just about covers it. :laughing:

I use synthetic in everything including my mowers.:thumbsup: