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Discussion Starter #1
I poked around but couldn’t find a thread discussing oil types.
What kind of oil motor oil do you recommend for a 1981cm400c with 25,000 miles, running at temperatures between 40F and 95F?
I must admit that I’ve been using conventional 10w40 in this bike for the last 15 years. I was not aware that motorcycle oil existed.
 

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Not surprising, this hasn't been discussed a whole lot.:roll:

The reason for motorcycle specific oils is that our clutches are bathed in oil and the friction reducers in modern automotive oils can interfere with their proper function. Just use an oil with an MA rating and of the viscosity recommended in your factory service manual. If you don't have a factory service manual (Clymer, Haines, etc do not count) we can help you to acquire one.
 

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Discussion Starter #3
My clutch does slip. Have I damaged it by using automotive oil, or will it start working better after a couple of oil changes?
 

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I run Rotella T4 10w-40, its cheap, JASO certified and plays nicely with my clutch.
 
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The clutch is soaked in the oil you've been running, there's little chance of getting rid of all the friction modifiers that are now embedded in the material. Auto oils have those modifiers in them, MC oils don't. I'd suggest replacing the clutch frictions and cleaning the steels in a degreaser solution.
 

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Discussion Starter #6
The clutch is soaked in the oil you've been running, there's little chance of getting rid of all the friction modifiers that are now embedded in the material. Auto oils have those modifiers in them, MC oils don't. I'd suggest replacing the clutch frictions and cleaning the steels in a degreaser solution.
But it’s only been about 15 years! ; )
 

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+1 on the Rotella, too - I've been running Rotella T6 (the 5w-40 synthetic stuff) since my last rebuild and it runs like a dream.
 

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Ditto
 

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A note on the Rotella, I used to run the regular T but it disappeared from shelves about a year ago. After much searching it seems Shell replaced T with T4.
 

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Everyone is going with Rotella so I'll play odd man out. Been using Castrol 4T for what seems like forever.
 

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Castrol for my bike and past race cars for years too.
 

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Rotella, It works well with clutch type and autos
 
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