Specific questions about car oil in B&S

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Marketing B.S. Just like how B&S and Kohler will market their oil filters as being "specifically designed to withstand the operating conditions of small engines" yet they are the cheapest constructed e-core filters I've ever seen.
They're not wrong...the BS/Kohler filters are specifically designed for the light duty service they will see in a small engine. A Fram Ultra would be overkill.
 
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Hello.

Without starting a religious war about this pre-discussed topic, I will try to specify my questions. I know all about the viscosity ratings in theory, so please do not focus on this.

I have just bought a machine with an almost unused Briggs & Stratton XR950. I can read from the manual that quite a few different oils can be used. I do not own motor oil at any kind at the moment, and the costs for any of the different oils from the manual is about the same for me. I will only use the machine in temperatures from 10 degrees Celsius (50 Fahrenheit) to 30 degrees Celsius (86 Fahrenheit). The oil will be changed annually.

1. Are motor oil for cars suitable for air-cooled garden machines?
1.1. Are the higher temperatures in the air-cooled motor a problem?
1.2. Can the additives in car engine oil be unsuitable for garden machines?
1.3. Are motorcycle oils in general preferred over car oils?

2. Can a fully synthetic oil be harmful for the motor?
2.1. In relation to this question, I can simply not understand why B&S differ in their recommended temperature ranges between 5w30 synthetic and non-synthetic. Viscosity-wise they should be identical.

3. Why the heck does not B&S recommend 10w40 oils instead of 15w50? It is a pretty long jump from SAE 30 oils.

In the end, I wonder if I should go with SAE 30 mineral lawnmower oil or 5w30 fully synthetic car oil (or maybe 10w40 fully synthetic car oil to be badass and go against B&S' recommendations). It is not that much a question of viscosity but more a question of oil quality. I might be too conservative thinking that the single grade oils are old-school and underdeveloped compared to modern multigrade car oils. The price is almost the same, and I will go with the best oil for this purpose.
Really, theres no reason to go SAE30 in that engine because theres nothing that SAE30 does that 5w-30 synthetic wouldnt and the synthetic would be better for the engine overall. Really, nowdays theres no reason to use straight 30 weight oil or anything mineral, unless its an older engine.
Beyond that, there really is no difference from car oil or lawn and garden engine oil.
 
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Really, theres no reason to go SAE30 in that engine because theres nothing that SAE30 does that 5w-30 synthetic wouldnt and the synthetic would be better for the engine overall. Really, nowdays theres no reason to use straight 30 weight oil or anything mineral, unless its an older engine.
Beyond that, there really is no difference from car oil or lawn and garden engine oil.
Higher HTHS?
 
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Really, theres no reason to go SAE30 in that engine because theres nothing that SAE30 does that 5w-30 synthetic wouldnt and the synthetic would be better for the engine overall. Really, nowdays theres no reason to use straight 30 weight oil or anything mineral, unless its an older engine.
Beyond that, there really is no difference from car oil or lawn and garden engine oil.
There's also no reason not to if the oil carries the proper license or approval and is suitable for the expecting starting conditions. If those two criteria are met there are only upsides. Monograde oils are "better oils" from that standpoint.
 
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"Monograde oils are an acceptable option if the equipment can provide excellent oil cooling and constant temperature control".

OPE is not famous for either of the above. Monograde oils thin out at high temperature and thicken at low temp. The difference between them and multigrade is the steepness of the line. I see the primary advantage of a monograde is the missing viscosity improvers. Keep in mind that modern additives are better today than decades ago,
and synthetic base stocks (PAO and Esters) have a native high viscosity index to begin with. Synthetic oils do not have a shear down or thermal / oxidation stability issue. Monograde oil solves a problem with multi-grade mineral oils, and this problem simply does not exist with high quality multigrade synthetics.

I fail to see a reason to prefer monograde over a high quality synthetic multigrade, but perhaps I am missing something. I am curious to hear rational argument to the contrary.

Take a look at this article if interested:
 
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Again, a monograde oil is entirely usable if the license is what's required and the starting temperatures are appropriate. The only benefit of a multi-grade oil is pumpability at low temperatures. That's it.
 
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"Monograde oils are an acceptable option if the equipment can provide excellent oil cooling and constant temperature control".

OPE is not famous for either of the above. Monograde oils thin out at high temperature and thicken at low temp. The difference between them and multigrade is the steepness of the line. I see the primary advantage of a monograde is the missing viscosity improvers. Keep in mind that modern additives are better today than decades ago,
and synthetic base stocks (PAO and Esters) have a native high viscosity index to begin with. Synthetic oils do not have a shear down or thermal / oxidation stability issue. Monograde oil solves a problem with multi-grade mineral oils, and this problem simply does not exist with high quality multigrade synthetics.

I fail to see a reason to prefer monograde over a high quality synthetic multigrade, but perhaps I am missing something. I am curious to hear rational argument to the contrary.

Take a look at this article if interested:
No oil has that problem, it is always the viscosity index improvers that shear (if mechanical shear is even a problem for the particular engine). No base oil shears regardless of whether it is synthetic or conventional.
 
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May 23, 2021
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No oil has that problem, it is always the viscosity index improvers that shear (if mechanical shear is even a problem for the particular engine). No base oil shears regardless of whether it is synthetic or conventional.
Correct. that is what I was talking about. It is just that synthetic base stocks require a lot less VII-s because the base stock is multi-viscous in and by itself.
 
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Yes, things have changed, and I believe that it is mostly the oils that have changed, not the engines. I am now using multigrade oils that were considered a no-no previously in my 45 year old rider with a Tecumseh engine.
Even at that, they always seemed to run forever with the oils of the day, whatever you used in it.

I think to some degree worrying too much about it is like counting the number of angels that fit on the head of a pin. Interesting, but ultimately not practical or useful. That B&S engine is going to run for 15 years on conventional oil if you change it with some kind of frequency, and it may run even longer if you use Euro-spec 5w-40 or diesel-rated 15w-40.

Keep in mind, one thing working in their favor is that neither the RPM nor the load is particularly high in small engines. Heat is the main concern.
 
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Some folks seem to approach their OPE-s as if they were not worth anything, or if these are the beggars who can't be choosers. "It gets the leftovers".

The "leftovers" from my Mercedes , or most people's cars requiring an SAE 30 or 40 oil, exceed the requirements specified by Honda and Brigs for my little motors. Leftovers are fine.
These same basic lawnmower engines used to run on non-detergent SAE 30 for decades.
I'm not that old and I remember Briggs and Tecumseh specifically stating in the manuals to only use SAE 30 oil, that SAE 40 and multigrades were too heavy for splash lubed motors (splash lubed was a little sheet metal tab on the conrod cap that splashed oil at the cam and cylinder when the crank rotated).
I had an 8hp Sears lawn tractor and the manual stated not to use synthetic oils because it would lead to high oil consumption.
Times change. Check the manual for your motor and read the spec required. It's usually whatever was sort of current when the manual was written. Nothing special.
 
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