I have the same 650cc rotax engine in my X-Challenge (and same clutch) and use ONLY full synthetic oil. (have done since the 10,000km mark)

As long as you use a motorcycle specific synthetic oil rather than a car synthetic oil, you will not get any clutch slip. A motorcycle synthetic oil is, after all, specifically designed for wet clutches!

The BMW manual says only that they do not recommend synth oils ONLY for the first 10,000k. I now have 50,000k on my engine, had it pulled apart a couple of weeks ago to check the head, and the mechanics actually asked me if it was a new cylinder. After 50,000k it still had that factory honed look.

For whats its worth, I took the advice of an excellent bike mechanic and use only Motul 300V (double ester) ... its expensive (10 quid a litre in the UK), but you have a several thousand dollar investment and you pour thousands more of dollars of fuel into it over its lifetime. There is only one thing that protects it from wear all its life, and that is the oil. Spend a couple more bux and get a good oil.

Oilman ... is this your site?

Motul 300 V 4T Factory Line 10W-40 Racing lubricant for race bikes 100% Synthetic – Double Ester

If so, I shall be buying form you in the near future.

That's us. Good post and well put

Cheers
Guy

Nice post Oilman.

I'm using full synthetic in my VW diesel and BMW car and have just switched over to synthetic in my R1200GS after the 10,000 km recommended by BWM. My R100GS has had nothing but dino oil in the engine and mostly synthetic in the transmission. The reason I stuck with dino oil is that I thought it would be more practical to do more frequent oil changes in developing countries where synthetic is not readily available. What would you suggest for a trans-Africa journey? Run synthetic as long as possible and then swap out to whatever is locally available, carry enough oil for a change half way down or simply run dino oil from the start, changing as often as practical?

I think we've all heard stories of synthetics causing more oil leaks in an older engine that has grown up on mineral oil. What is the current state of affairs with synthetics? Would putting synthetic in my 230,000 km R100 cause the pushrod tube seals to start leaking?

I like it here..[bear with me]
 

This is why I like the info that comes through Horizons - people are driven by the necessity of high mileages and the inconvenience of cost. A perfect situation to find out, practically at least, what works and what doesn't.

The average annual mileage of motorcycles in the UK is something like 1 or 2 minor service intervals and model ownership is probably a couple of years. So it stands to reason that the average post about oil/observed failure on any given forum has such a biase due to low mileage experience as to render its validity entirely questionable and highly influenced by the statistical 'bathtub' curve of mechanical failure (e.g. bad day at the factory etc.) than any real difference between one motorcycle oil and another.

What do you lot think? I sense an 'elephant in the room'.

The stories about leaking seals are based on older synthetics, not modern ones, so no need to worry about that. The only other reason for a synthetic to leak more is that if the engine has not been particularily well looked after and there is a lot of wear. If the synthetic is thinner than the mineral oil, there may be some leakage.

If you are worried about that, go for one of the hydrocracked synthetics, something like the Silkolene Comp4 or Motul 5100 as they are highly refined and modified mineral oils.

Cheers

Tim