Well at 16k miles after only using YamaLube (I had no idea it was the worst oil on the market) I had carbon build up on the intake valves, I switched over to Amsoil and by the next oil change the valves were crystal clean. AND YES I KNOW it should not really effect the intake valves since they are being sprayed with fuel the entire time and should not ever come in contact with engine oil (but the crankcase does breath through the airbox), but I have honestly refueled at the same Exxon near my house every of the time (I have to refuel at different places away from home on long trips, obviously), but I can't realy quantify it but it happened. And yes the seat is AWESOME.
engine oil has NOTHING to do with intake valve buildup. zip. nada. The only way it would is if you had some leaking valve guide seals, where oil was running down the valve stem. However IF that were the case you would get smoke on start up.. like my 295,000 mile Acura vigor
And if you had leaking guide seals, you would have leaking guide seals with oil 'A' and oil 'B'.
You get 2 things on your intake valves . 1-AIR 2-FUEL . So if you had any buildup, it was from a crazy rich a/f condition, or a LEAKING INJECTOR.
Oil in the airbox from pcv (positive crankcase ventilation) has nothing to do with this either unless you were crazy overfull with oil, or the bike tipped over and some oil ran up the breather hose.
The KIND of oil you ran in the engine, had nothing to do with "buildup" on the intakes. And for what it's worth, the CARBON build up that occurs on exhaust valves, won't even come off with the valve spun in a drill and wrapped with scotchbright pads. We try. Carbon - infant diamonds. hard.
so it's kind of laughable to think carbon would come off instantly with an engine oil change or from the marketing gimmickry the gas companies would try to have you believe.
just saying .. no offense.