This video has been viewed almost 6 million times, so there's a good chance some BITOG members have seen it, but for those who haven't it's very interesting:
"Is Synthetic Motor Oil Better For Your Car?" (Not the best title...)
https://www.youtube.com/watch?v=tYkg0oDUXs8
It deals mostly with viscosity breakdown and explains how synthetic 5W-30 oil already has the properties of a 5W-30 to begin with, before the addition of additives -- while 5W-30 dino oil starts out as 5 weight and relies on the additives for the 5W-30 multi-grade designation.
Conventional 5W-30 eventually thins out, whereas synthetic retains it's viscosity rating much longer.
I found that video in this R&T article:
"What Makes Synthetic Oil Better?"
https://www.roadandtrack.com/car-culture/a12007368/what-makes-synthetic-oil-better/
The article says, quote:
"When it's brand new, a 5W-30 conventional motor oil acts exactly like a 5W-30 synthetic motor oil.
Over time, however, the chemical additives used in the conventional oil to alter its properties begin to break-down, vaporize, or get used up. This means that the oil starts to return back to it's original base oil, from a 5W-30 back to a straight grade 5 oil for our example. As contaminants begin to work their way into the oil, the overall trend over a long duration is that the oil thickens across the entire spectrum. An old and used conventional 5W-30 oil behave very differently than a brand new 5W-30.
Synthetic oils work quite differently. From the start, the chemical structure is designed to match a specific multi-grade oil. That means even without additives, you could have a 5W-30 motor oil, and then certain additives like rust-inhibitors or dispersants will be added to further improve the usefulness of the oil. The result is that over time the synthetic oil does not degrade away back to a less desirable oil as conventional ones do. From a viscosity standpoint, an old 5W-30 synthetic will act pretty similar to a new 5W-30 synthetic, although likely it will be slightly thicker as a result of contaminants."
~
Conventional oil continues to be recommended by many auto and small engine mfrs, so clearly the viscosity breakdown of multi-grade dino oils is not a significant issue for most vehicles and small engines, as long as oil change intervals are followed. Honda recommends 30W / 5W-30 / or 10W-30 conventional oil up to 110*F in their air-cooled lawnmower engines -- with no mention of synthetic at all.
All I can guess is that B&S is assuming the absolute worst case when it says 5W-30 dino oil should only be used below 40*F. As the article (and video) state both types of 5W-30 start out the same. B&S must be assuming that the oil will not be changed when it should be. If it was really that bad, Honda would not recommend it and say it's good to 110*F.
~
Speaking of oil change intervals, the video explains that even though synthetic oil is superior in many ways, the additives become depleted, which is why mfrs say that oil change intervals cannot be lengthened when using synthetic.
"Is Synthetic Motor Oil Better For Your Car?" (Not the best title...)
https://www.youtube.com/watch?v=tYkg0oDUXs8
It deals mostly with viscosity breakdown and explains how synthetic 5W-30 oil already has the properties of a 5W-30 to begin with, before the addition of additives -- while 5W-30 dino oil starts out as 5 weight and relies on the additives for the 5W-30 multi-grade designation.
Conventional 5W-30 eventually thins out, whereas synthetic retains it's viscosity rating much longer.
I found that video in this R&T article:
"What Makes Synthetic Oil Better?"
https://www.roadandtrack.com/car-culture/a12007368/what-makes-synthetic-oil-better/
The article says, quote:
"When it's brand new, a 5W-30 conventional motor oil acts exactly like a 5W-30 synthetic motor oil.
Over time, however, the chemical additives used in the conventional oil to alter its properties begin to break-down, vaporize, or get used up. This means that the oil starts to return back to it's original base oil, from a 5W-30 back to a straight grade 5 oil for our example. As contaminants begin to work their way into the oil, the overall trend over a long duration is that the oil thickens across the entire spectrum. An old and used conventional 5W-30 oil behave very differently than a brand new 5W-30.
Synthetic oils work quite differently. From the start, the chemical structure is designed to match a specific multi-grade oil. That means even without additives, you could have a 5W-30 motor oil, and then certain additives like rust-inhibitors or dispersants will be added to further improve the usefulness of the oil. The result is that over time the synthetic oil does not degrade away back to a less desirable oil as conventional ones do. From a viscosity standpoint, an old 5W-30 synthetic will act pretty similar to a new 5W-30 synthetic, although likely it will be slightly thicker as a result of contaminants."
~
Conventional oil continues to be recommended by many auto and small engine mfrs, so clearly the viscosity breakdown of multi-grade dino oils is not a significant issue for most vehicles and small engines, as long as oil change intervals are followed. Honda recommends 30W / 5W-30 / or 10W-30 conventional oil up to 110*F in their air-cooled lawnmower engines -- with no mention of synthetic at all.
All I can guess is that B&S is assuming the absolute worst case when it says 5W-30 dino oil should only be used below 40*F. As the article (and video) state both types of 5W-30 start out the same. B&S must be assuming that the oil will not be changed when it should be. If it was really that bad, Honda would not recommend it and say it's good to 110*F.
~
Speaking of oil change intervals, the video explains that even though synthetic oil is superior in many ways, the additives become depleted, which is why mfrs say that oil change intervals cannot be lengthened when using synthetic.
