Oil weights (10w30 vs 10w60) | GTAMotorcycle.com

Oil weights (10w30 vs 10w60)

Wyled

Well-known member
Okay so maybe this has been answered before but I haven't found any information on it. I also tried googling but almost all answers don't directly answer the question or some just confuse me more.

Basically I'm wondering what the difference would be between a certain weight of oil, say 10w30, and another oil that covers a larger range of temperature, say 10w60. Would it not be more beneficial to use the 10w60 since A.) it covers the 10w30's range and B.) it offers more coverage in higher temperatures on top of that?

That being said, could I theoretically use a 5w30 over a 10w30? Or, a 0w30 over a 10w30? Because if the former is true and benefits are added it would go both ways i assume.

For the sake of argument lets just pretend regardless of brand or composition to assume it's the same brand, same formula and same synthetic composition. Personally I run 10w40 in my Honda but I found some 10w50's, 10w60's AND 5w40 that would be cheaper.


Can anyone give me a straight undisputed response or maybe their best take?

Thanks!
 
You are absolutely and completely misinformed about what those numbers mean.

The two numbers are related to the absolute viscosity ("thickness") of the oil at two specified, fixed temperatures. 10w60 does not "cover a larger range of temperature". It has a higher absolute viscosity at a specified temperature (which is meant to coincide with normal engine operating temperature when warmed up).

10w60 is not "better" than 10w30 ... unless your engine was designed to use 10w60.

10w30 may be "better" than 10w60 ... if the engine manufacturer designed the engine to use 10w30.

Use what the owner's book specifies.
 
never heard of 10W60, though it may exist

the higher the differential in those 2 numbers
the more elaborate the polymer package will be

polymers are synthetic strands in the oil that change shape under heat
when you read about oil shear-down, that's what they're talking about
the more polymers in the oil the shorter the life from the shear down
over time and use that high number will become lower

like above, use what the manu recommends
 
My Guzzi runs 10W60. I believe some BMWs and VWs, as well. Perhaps others.

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Everything one will ever need to know about motor oil can be found here: Bob Is The Oil Guy | The Internet's Number One Motor Oil Site
 
As per the manual. They really do know best.
 
It's not crazy to take this question seriously, as I have owned more than one bike that has a strange oil viscosity chart that basically extends into infinity at either end.

For the sake of argument lets just pretend regardless of brand or composition to assume it's the same brand, same formula and same synthetic composition. Personally I run 10w40 in my Honda but I found some 10w50's, 10w60's AND 5w40 that would be cheaper.


Can anyone give me a straight undisputed response or maybe their best take?

Thanks!

Perfect. On that premise, the larger the difference between those two numbers, the worse the oil. What J_F said - the greater the range, the more the oil is relying on viscosity modifiers, and the faster the oil shears down to a lower viscosity range over time when in use.

Also though - engines tolerate the lower number being different better than tolerating the higher number being different e.g. running 0w40 or 15w40 in a bike meant to take 10w40 is somewhat safe. Running 10w60 is not - the oil will have a higher viscosity at normal operating temperature, and the lubrication system is designed around assumptions and restrictions to achieve certain pressure and flow characteristics. So if your engine is running in pressure relief (max oil pressure), if the oil viscosity is unnecessarily high you now may be starving the valvetrain of oil. Which is bad! And if the viscosity at operating temperature is too low, the engine may never achieve max oil pressure, so it is operating in a permanent state of low oil pressure. Also bad.

Things get more complicated than that because the difference in cold and hot viscosity for any oil is HUGE and the system is somewhat designed to accommodate that (but it also assumes things like the operator knows not to "race the engine" when it is cold)
 
Lots of newer automotive engines are designed for 5w20 or 0w20. If you use thick stuff, it doesn't start pumping as quickly in a cold start. Use what the owner's book recommends.
 

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