He said they only use Castrol 10-40 conventional as they have seen too many using a synthetic have clutch slippage.
Ask if he ever seen a new bike clutch slipped using synthetics??? I bet the answer is going to be no and here is why...
The holy trinity of science is 1)Reason 2)Observation 3)Experience...
employing those tools we observe that the primary cause clutch slip
are high mileage... mileage is the constant among all of the clutches
that begin to slip... oil choice whether synthetic or not is not a
constant... High mileage is the constant where all clutches begin to
loose grip due to normal glazing and contaminates that build up over use...
I recently bought some Mobil 1 10-40 4T bike oil and am wondering whether to heed the shops suggestion?
Ask enough shops and the majority favor synthetic oils including my shop...
Understanding synthetics means more refining to remove less desirable
elements from crude until what’s left is mostly higher-performing
molecular structures. Waxy stuff had to go because it made oil congeal
at winter temperatures. Aromatics had to go because they lost
viscosity too rapidly when hot. Unsaturates had to go because they
were vulnerable to heat-driven gumming and sludging. And so on.
Synthetics were refined from crude to give owners advantages conventional oils could not...
technically speaking they will meet and exceed your mileage expectations...
Manufacture synthetic goals refined from good old crude oil..
Higher viscosity index
Better viscosity stability at varied temperatures
Better chemical and shear stability
Consistent fluidity
Better lubricity at low temperatures
Faster lubrication at start-up in low temperatures
Resistance to oxidation (thickening), thermal breakdown, and oil sludge problem
Excellent protection at high temperatures
Engine cleanliness
Outstanding protection against harmful deposits
Cleaner running engines
Lower oil evaporation
More engine power
Lower maintenance cost
Me and my GPz 550 enjoying the synthetic advantage with no clutch grip problems due to the purity of the oil...