I've copied this message from a Virago list that I'm on. It could be very pertinent to any KDXer who runs Mobil 1 in his gearbox:
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I have long recommended Mobil 1 15W -50 TRI-SYNTHETIC oil for use in the
> Virago as one of the best automotive oils you can use and a lot better than
> dyno motorcycle specific oils.
>
> The synthetic formula holds up to the heat and shearing effect of motorcycle
> engines much better than the dyno juice and the OLDER TRI-SYNTHETIC Mobil 1
> meets that challenge to a tee with no clutch slipping like the motorcycle
> specific, overpriced, and over B.S.ed oils claim it would.
>
> Now a new kicker comes in to play. The new Mobil 1 15W-50 SUPER-SYNTHETIC
> with the new SL automotive rating takes out more of the zinc and phosphorous
> that protects the engine and adds a considerable amount of friction
> modifiers that could cause clutch slippage.
>
> It is a much better automotive oil that was formulated to meet the demands
> of automotive manufacturers in their newer engines with tighter tolerances
> and lower viscosity requirements. The new formula takes longer oil change
> intervals into account due to the enormous amount of un-maintained leased
> vehicles out there now.
>
> I am on other motorcycle lists and the word is that clutch slippage is now a
> factor with the SUPER-SYNTHETIC.
>
> So what is better for the car has finally put the knife into the bike. I no
> longer think that Mobil 1 automotive is a good affordable oil of choice for
> the Virago like it used to be.
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---------------------------------------
I have long recommended Mobil 1 15W -50 TRI-SYNTHETIC oil for use in the
> Virago as one of the best automotive oils you can use and a lot better than
> dyno motorcycle specific oils.
>
> The synthetic formula holds up to the heat and shearing effect of motorcycle
> engines much better than the dyno juice and the OLDER TRI-SYNTHETIC Mobil 1
> meets that challenge to a tee with no clutch slipping like the motorcycle
> specific, overpriced, and over B.S.ed oils claim it would.
>
> Now a new kicker comes in to play. The new Mobil 1 15W-50 SUPER-SYNTHETIC
> with the new SL automotive rating takes out more of the zinc and phosphorous
> that protects the engine and adds a considerable amount of friction
> modifiers that could cause clutch slippage.
>
> It is a much better automotive oil that was formulated to meet the demands
> of automotive manufacturers in their newer engines with tighter tolerances
> and lower viscosity requirements. The new formula takes longer oil change
> intervals into account due to the enormous amount of un-maintained leased
> vehicles out there now.
>
> I am on other motorcycle lists and the word is that clutch slippage is now a
> factor with the SUPER-SYNTHETIC.
>
> So what is better for the car has finally put the knife into the bike. I no
> longer think that Mobil 1 automotive is a good affordable oil of choice for
> the Virago like it used to be.
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