www.zxrworld.co.uk

Hi, I recently moved house and went to my new local bike shop (JT's motorcycles, a large reputable dealers) to buy some oil. I've always put Silkolene comp 4, 10w40 fully synthetic in my bike but when I asked if they had any comp 4 they said they only ever put Silkolene super 4 semi synthetic in all the bikes they work on as apparently fully synthetic causes early clutch slippage.
I never experienced any clutch slippage for the first year and when I did, I put it down to worn clutch plates. I have no idea how old they were as they were the ones in the bike when I bought it. I put in an EBC street race clutch set which replaced the fibre plates, metal plates and springs. I never measured the thickness of the old plates so I don't know how worn they were. 15000 miles on there's still no problem with my new clutch (I'm still using fully synthetic)
I ride mostly on the road but give it a proper thrashing and mainly stay above 10,000 revs. The bike sits midway on the temperature gauge. I change the oil and filter every 2000 miles.
So my questions are
-Am I correct that fully synthetic is better for the engine, especially when being used hard?
-Has anyone had problems with clutch slippage using silkolene comp 4 fully synthetic?
-Is it possible for my clutch to prematurely start slipping after say 15,000 miles instead of after 30,000 miles if I use fully synthetic?
- if that is the case, is it worth using the fully synthetic for the engines sake, and just replace the clutch plates more often?
Thank you

Hi There,

I can only speak from what I have experienced, but after I put fully synthetic comp 4 in my ZXR, that was when my clutch started slipping (immediately after the change,) which logically points to the oil being the source.

People often argue that fully synthetic causes clutch slip due to being more 'slippery' but technically speaking it isn't, it's just some fully synthetic oils have additives that disagree with some clutch configurations. And yes, technically speaking, fully synthetic is better for a high performance engine. This is because it can be better tailored to have specific properties to help it last longer etc. This is however not to say that by using semi-synthetic, your engine is going to wear more quickly and easily.

Anyway, you will hear accounts on both sides of the story, some will say they experienced slippage, some will say that everything was fine. If I were you, i'd just stick to what you know will work, and go with semi-synthetic. Going for semi over fully is not going to cause any noticeable effect on the life of your engine whatsoever, so like I say, i'd stick with the safe bet.

And to answer your last question, I would rather go for the semi and replace the oil more frequently, than keep attempting to replace the friction plates with the fully synthetic oil!

Anyway, I hope this helps you out!

Jamie

Ah, just noticed you're already using the oil. If you are using the fully synthetic oil, and are experiencing no problems, i'd just stick with it!

Cheers for the reply.
I think I'll keep using the fully synthetic as I have no problems with it yet but in the future when my clutch starts slipping I might swap to semi synthetic and see if it stops the slippage.
And you're right, you hear so many different things from different people

I can highly recommend you fully synthetic oil based on ester instead of silicone. This is the fully oil with no clutch slipping! However if you don´t have problems with yours that will be fine, too. If your clutch starts slipping but you still want to use fully synthetic ester should be your choice