Specific questions about car oil in B&S

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May 10, 2021
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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.
 
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To answer a few questions: Yes, you can use a car oil in a lawn mower.

Yes, air-cooled equipment can reach hot temperatures.

No, car oil is fine in a lawn mower or any air-cooled outdoor power equipment.

Many folks on here use a diesel oil on here be cause there are not as many restrictions on the additives in the oil compared to car oil.

No, a fully synthetic oil is just fine in a lawnmower.

A conventional 5w30 shears in the heat a lot more compared to a synthetic 5w30.

They recommend the 15w50 for commercial applications where the lawn mower will be used all day.

I personally use a 10w30 synthetic with great results.

If a 5w30 synthetic and a 15w50 are allowed in the same engine, anything in between will work well, too.
 
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I use the 10w40 Kawasaki oil i have left over from my 4 stroke motorcycles. My 20 year old toro personal pace seems to like it fine.
 
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OPE engines fail because of lack of oil and/or lack of maintenance, not because someone chose 5w-30 over 10w-40 etc...

For the normal homeowner, checking the oil level semi-regularly and changing the oil every year or two will result in the engine out living the rest of the machine.
 
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The latest B&S oil guide states that 5w30 synthetic is the preferred oil.
Well, they don't make a synthetic 10w30.

They recommend the syn 5w30 for lawn mower, pressure washers, generators and snow blowers.

Funny how they also reccomend "never chaning the oil", too. Do you follow their reccomendation for that?
 
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1. Depends on the small engine manufacturer. Some spec SG/SH/SJ oils... usually higher z/s/p content. I have worked for small engine parts manufacturers and will say that "cost" is more important than quality.
1.1 Definitely, and why I use synthetic oil and an oil with HTHS(commonly higher grade).
1.2 I'd say "in the right dose". The movement toward saving emissions control devices, and possibly not saving the engine, is a cult.
1.3 Some, but not all, have the higher z/s/p doses that I'd recommend. So, use the motorcycle or diesel engine oils, or 4 cycle specific small engine oils!
2. That depends on the API/ILSAC level of performance. I'd say SpGF6 looks to protect the engine some more... thank the automakers for LSPI and fuel dilution causing timing/vvt systems to fail. We'll see in a decade if the engine noise complaint rate has reduced. 1st oil spec to protect a timing chain. How long have we used timing chains?
2.1 Oil grade recommendations are a krapshoot and usually written by tech writers that don't have a clue. Viscosity, HTHS, will not be identical. You can have a 30 grade oil with an HTHS of 2.9 or 4.0... or 9.4cst to 12.4cst.... pretty broad range!
3. See 2.1.

My recommendation is:
Full synthetic oil, in whatever grade you want for your weather. Stick with HDEO, motorcycle oils, or known boutique oils. Look at the VOA/UOA section to see what oils have 'stay in grade HTHS' and/or a little more additives.

Since some smaller engines don't have real oil pumps or oil filtration, adjust your hourly oil change interval as needed. And, consider drain plug or dipstick magnets, if available.

Buy a bottle of the BriggsStratton 5w30 synthetic oil and send it out for a VOA. Then, compare it to ANY of the automotive oils in this forums UOA/VOA section. Can also do the same with the Honda synthetic HP4s 10w30 too.
 
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Synthetic 10w30 seems to be a great option, as well as any HDEO. The important thing is keeping it full (especially on splash lubed engines) and changing it to remove contaminants.

While I don't agree with Briggs' "never change the oil" marketing, I doubt it will really impact longevity of equipment for the average homeowner, considering how many old machines come to me with the original oil in them.

Personally I run mostly HDEO like a 5w40 or 15w40 because I own a lot of older equipment, some of it burns oil, but any 5w30, 10w30, 10w40, etc will work fine as long as you maintain a proper oil level.
 
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Only small selected B&S engines are stated to not needed oil changes. Larger B&S engines have a 50 hour oil change interval. We should not make generalized statements if we are not fully informed. Ed
 
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Just to add a little more info, Valvoline Motorcycle is a Full Synthetic, 10W40, that "meets or exceeds" API SL.
It's also $8.00 a quart at AZ!
 
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I saw the back of a lawn mowing service trailer with Pennzoil Yellow Bottle commonly used in cars and trucks.
I suspect, they are fine.

Despite, your belief, the engine will not know any difference.
All it needs oil.
 
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I think things have changed over the years but the last B&S engine I had recommended straight 30 weight. At the time they claimed multi viscosity oils in their engines could cause excessive oil consumption. The mowers I have now have Kohler engines on them I think I've ran both regular automotive grade straight 30 weight and 10w40 without issues.
 
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I think things have changed over the years but the last B&S engine I had recommended straight 30 weight. At the time they claimed multi viscosity oils in their engines could cause excessive oil consumption. The mowers I have now have Kohler engines on them I think I've ran both regular automotive grade straight 30 weight and 10w40 without issues.
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.
 
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