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Discussion Starter · #1 ·
so for a cbr500r honda recommends Honda GN4 10w30 in Québec, Canada. if i put a higher oil grade like the GN4 10w40 will it affect the smoothness of the motor/clutch/transmision by makin it more rough or could it be just a result of having too much oil in the motor?
 

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10/30 grade would be the preferred choice as recommended by Honda, but 10/40 is absolutely fine. As a matter of interest and this is by no means finger pointing at any one brand of oil, I wanted to use fully synthetic oil (my personal choice) and fully synthetic is really expensive in 10/30 so I bought a cheaper brand with the same spec as the expensive oil. What I did find was foaming in the sight glass which I hadn't noticed before. So I went back to my expensive oil and guess what no foaming. So you pay your money and take your chance. That said you do not need to buy Honda oil. My dealer uses Motul.
 

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Discussion Starter · #3 ·
10/30 grade would be the preferred choice as recommended by Honda, but 10/40 is absolutely fine. As a matter of interest and this is by no means finger pointing at any one brand of oil, I wanted to use fully synthetic oil (my personal choice) and fully synthetic is really expensive in 10/30 so I bought a cheaper brand with the same spec as the expensive oil. What I did find was foaming in the sight glass which I hadn't noticed before. So I went back to my expensive oil and guess what no foaming. So you pay your money and take your chance. That said you do not need to buy Honda oil. My dealer uses Motul.
changing to 10/40 from 10/30 could it make it run rougher especially for shifting gears? or would it be a result of too much oil in the engine/transmision?
 

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Oil viscosity rating is actually a range. An analogy as follows:
..W30 is a range from W30...39.
..W40 is a range from W40...49.

The higher end of W30 is very close to a W40. Similarly, the higher end of W40 is very close to W50. The actual oil viscosity 'Cst' rating is usually published in the technical datasheet from the oil manufacturer's web site.

I do "feel" that my bike prefers lower viscosity oil (W30); it seems to idle smoother and quieter; gear shift lever felt more 'clicky' (less 'sticky') during changes . Air temperature is between 5'C to 29'C.
In hotter summer climate over 30+'C (air temperature), W30 oil felt a little "thin" and W40 actually felt better. But at those temperature, I try not to ride much anyway, getting too hot for comfort.
With W40, I prefer oil that is rated at the lower end of 'Cst' rating (closer to W30).

Any oil with JASO rating can be used for the bike. There are car engine oil that has JASO rating (only a few though) and they are usually cheaper.
 

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OK , what is this about to much oil. Why do you ask this?
If you are to use 3 liters - only put in 3 liters and it wont be to much.
Lets get the viscosity straight.
IF your engine says to use 10w30, going to 5w30 or 5w20 IS NOT BETTER FOR IT!
There are two numbers given for oil because it changes its thickness with temps.
With 10w30 -
the 10 weight is the thickness at lower temps
the 30 weight is the thickness at higher temps
You will read about people in Arizona and Texas using 10w40 or even 20w50 because they have higher temps and possibly the higher viscosity might be better for them - possibly.
If the engine calls out for 10w30, you can use 10w40 no problem, but with the modern engines and the tight tolerances I'd stick with the oil weight recommendations.
Being able to "tell from feel" that the engine runs better with a certain weight oil - Then you should rent yourself out because you could make a lot of money if your so sensitive to that!!
DO NOT use car oil in a bike. Car oil usually has friction modifiers to reduce gas usage and will make your clutch go bad!
 

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Discussion Starter · #9 ·
OK , what is this about to much oil. Why do you ask this?
If you are to use 3 liters - only put in 3 liters and it wont be to much.
Lets get the viscosity straight.
IF your engine says to use 10w30, going to 5w30 or 5w20 IS NOT BETTER FOR IT!
There are two numbers given for oil because it changes its thickness with temps.
With 10w30 -
the 10 weight is the thickness at lower temps
the 30 weight is the thickness at higher temps
You will read about people in Arizona and Texas using 10w40 or even 20w50 because they have higher temps and possibly the higher viscosity might be better for them - possibly.
If the engine calls out for 10w30, you can use 10w40 no problem, but with the modern engines and the tight tolerances I'd stick with the oil weight recommendations.
Being able to "tell from feel" that the engine runs better with a certain weight oil - Then you should rent yourself out because you could make a lot of money if your so sensitive to that!!
DO NOT use car oil in a bike. Car oil usually has friction modifiers to reduce gas usage and will make your clutch go bad!
i was just asking if the viscosity could affect how the engine runs or if it was the result of having too much oil in it. its a simple question tbh no need to pop a blood vessel and write a whole essay on it jeez.
 

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Oil level should not be above the full line.
Viscosity cant affect running. It can but under extreme conditions.

My rant was to the others that seem to not understand oil weight.
And thinking they can tell the difference between 30 and 40 weight oil in their engine!!

Your question from the first post -
"if i put a higher oil grade like the GN4 10w40 will it affect the smoothness of the motor/clutch/transmision by makin it more rough or could it be just a result of having too much oil in the motor? "
Again I ask what was the problem?
Over full oil most likely will not cause rough running. How over full was it?
10w40 will also not make it run rough, or cause hard shifting.
 

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In case I missed it, the oil grade numbers are actually the viscosity numbers for the oil at 2 different temperatures. The first number is the viscosity of the oil when cold (room temp), and the second number is the viscosity of the oil when hot. For example, a 10W-30 motor oil means the viscosity is at 10W when the engine is cold and 30W when the engine is hot. The viscocity number is actually a measurement of time. ie a small measured amount of oil is put on an inclined surface and the time required for the oil to flow a certain distance is measured, hence a 10W oil requires 10 seconds to flow the required distance, where as a 40W oil requires 40 seconds to flow the same distance. This means a 40W oil is more viscous (thicker) than a 10W oil. Most liquids become less viscous as they are heated (this is the case for natural pure oil), but multigrade oils are carefully blended to become thicker as they are heated, this allows the oil to stay on lubricated surfaces longer and provide better lubrication as the engine works harder (and gets hotter). The original question of wether a 10W40 oil would make gear shifting harder than a 10W30 oil, is probably not (it probably even improves the action), firstly the thicker oil is only going to be effective at high engine temperatures, and the small change in viscosity probably would not affect anything, however as the oil also lubricates the clutch, a thicker oil can sometimes cause the clutch plates to slip, but that is very rare!! Usually going up or down one grade has no noticable effect on a motorcycle engine, what is more critical is to make sure the oil you use does NOT contain friction modifiers as those will cause the clutch to slip, so ONLY use an oil that is rated for wet clutch use (ie most motorcycle oils, NOT car engine oils!).
Having too much oil in an engine can cause internal & external seals to be blown and will often cause oil vapor to be blown out of the engine breathers, causing a mess and potentially getting oil on the rear tyre! Too little oil can cause the oil to froth up and can cause oil starvation which will lead to an engine seizure. It is important to keep the oil level within the manufacturers recommended limits.
Hope that explains it a bit..
 
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