Someone told me recently that running fully synthetic oil in a performance bike (read that as very high revving) with a wet clutch is not good and causes clutch slip.

I'm changing my oil tonight in preparation for a Donington trackday tomorrow and all I have is Castrol R4 fully synthetic oil.

I've also just installed some new clutch components...Friction plates and 1st gear steel plate.

Now I'm asking advice from those that run this specific oil in their sports bikes, not those that run other fully synthetic oils.

The question is, have you had any issues with it?

The next question is, if fully synth causes these problems, what good is it and why is it sold?

Thanks in advance.

I´m not sure, but i think that fully synth is to thin and doesn´t hold to well to the engine components, almost leaving them dry fo lubrication?

a semi-synth is thicker and therefore holds better to the components?

don´t know....might be talkin a load of rubish, but I also heard someone saying this but can´t remember where or who

I think you're right JP...Damn...Just found some Havoline 5W-30 semi synth oil. Not enough to fill the bike adequately enough...BUT...Could I mix this with the Castrol to fill the bike?

Something tells me this is not a good idea though?

uck it...There are enough people around the world (google search) running R4 in a range of bikes without problems, and I've been running it for almost 8000 miles without any so it can't be that bad to use fully synth oil.

Thanks for the info anyway JP.

Not really sure as I've only experience with the oil cooled suzuki's, but I know fully synthetic causes clutch slip on them.
One thing to check is did you soak the plates in oil before you fit them? Also I wouldn't mix semi and fully synthetic oils together.

mixin semi and fully synth is not a good idea! its right what jp says about semi synth being heavier and sticky, im gonna try running it in my fz6 (same engine as yours) but not because of clutch slip but because of the amount of clatter and noise my bike is making, its pissin me of and hopefully semi synth will quiet it down a bit!

i've never experienced clutch slip on my bike and have always used fully synth, the castrol stuff seems better than the motul sh!t ive got in now which i think thins out at higher temperatures hence the extra noises i can hear

Just been reading up on oils and motorcycle oil is made up differently for motorcycles as air cooled motors run approx 60% hotter than car engines.
R4 oil is ideal for your needs and all oils are not the same as the addative is different for eng/clutch use than it is for engine only.

I had an xjr the recomended oil was mobil 1 fully syn, yet this oil did not contain properties that made the clutch slip, most riders used semi syn and had no problems but my bike always hwd a sticking clutch until fully syn was used.
I will dig out the web site for all to read asap..

Think this may be of use to help you on??


http://www.atis.net/oil_faq.html

put whatever oil the maufacturer says to put in it. yamaha san know a bit more about bikes than any mates youll ever meet and any bike shop mechs too. trust them, put the oil that they recommend in the bike.

back to tellies, mine is a very flash phillips big fatscreen thing, they reckon i should run it on uk voltage , but i wonder if a bit more juice would make the picture better. doh, 450 volts and it died. bollox!

Yamaha's OEM oil is called Yamilube strangly enough and is actually Motul Semi-Synth. Semi-synth is too slippery and you will spin the clutch up all the time. Trust me on this, I have been down this road and know from personal experience.

Do you mean fully synth?

Sorry mate, meant full synth. Too much amber nectar last night.

Ideally fully synth oil should be used in bikes with either dry clutches, as Ducatti's have or bikes with a dry sump mechanism. Most bikes run their clutch in an oil bath and so it abvisable to contact the manufacturer to find out if fully synthetic oil is suitable. To be honest Semi synthetic oil is perfectly good for most bike applications, and I would only consider fully synth oil for an all out race prepared bike, never in a road bike even if it is to be used on the track from time to time. People do run some bikes on Fully synth oil but to be honest they are wasting their money.

Big, sticky mineral for me please, I get clutch spin on anything but, and it's cheaper too.
Just like Mr Yamaha and Mr Haynes reccommends

yea, im def gonna change mine from fully synth to semi, although i dont have any clutch slip i am hoping that it will quieten the top end a bit! i checked my valve clearances because of a strange tick as you can see in my avatar, this was a waste of time however as they were all fine! oh well. i have sinse discovered that it is the legendary "yamaha tick" and is completely normal, but hopefully semi oil will stick better at higher temps and make things quieter!

Well the oil seemed to hold out well...The clutch plates are now worn in after 200 miles and 10,000 RPM plus engine use (on track).

I don't know, I'll see what happens when the next oil change is due. I tend to change mine every 1000 miles.