The only reason a bike would use oil over 600km without leaking out would be because it is burning it in the combustion chamber, do a compression test...it will chew more of the synthetic stuff than dino if the synthetic is of lower viscosity, which they usually are.

 

Bike has only done 2000 miles - 1400 when I set off on the 600 mile trip over which level dropped from max to min. If it ever stops raining here think I'll go for a couple of hundred mile trip and see if level changes. But surely bike's a bit infantile to need a compression test. I'd resolved based on the deauville Forum comments to out that one back on semi-synthetic but............maybe I should stick with the synth a bit longer to see if any further unexplained loss - I understand oil can't vaporise but is it likely to be passing the rings in a bike this new? And why the Synth when the semi never did? i'm new to this stuff and confused. I thought I was giving them best available (Silkolene ester based fully synth Comp 4 20W-50) so surprised by the level loss. But........
Mike

 

I see u had done a filter change when u went to synthetic, did u run the bike after first filling and the top up after the filter gets primed as the level would drop about the 600ml u r talking about?

 

You understand incorrectly. Motor oil can and does vaporize. But not all vaporize at the same rate. And oil can slip past the oil control rings. An example is the Nissan VQ35HR motor. They put in thin oil rings to squeaze out a few more HP. They ended up replacing a whole lot of engines that went through more than a qt. of oil in less than 600 miles.

 

Ya I should have said that unless it's being burned or leaking out, the only reason is that it wasn't full. That's what I was driving at.

 

Bottom line:

Full synth is fine in motorcycles with wet clutches as long as:

It is NOT ENERGY SAVING (as seen in the little circle on the label)
The additives can cause clutch slipping

It is JASO-MA rated
That means it is rated for use in motorcycles with wet clutches.

Any other statements are simply not factual

 

Oh, and btw

Castrol Rotella T-6 full synth is my lube of choice. (used to run Rotella T dino, both are superb, inexpensive oils)

 

i used castrol oil 10w40, made for motorcycles, then went to mobil1 full synthetic 10w40 motorcycle racing oil and noticed no difference whatsoever