I ran one case of Amsoil 10W-40 4T through my ZZR 1200. Had to set the idle up slightly, fuel mileage dropped slightly, and shifting required slightly more effort. Went back to the Mobil 1 4T 10W-40, it went back to the way it was; Set the idle back down, fuel mileage went back up a mile or two per gallon and shifting smoothed out. At a rally in Montana, one of the Canadian guys commented on how quiet the motor ran, with very little valve or camchain rattle. (He had one of the same year and similar mileage) Always went 6,000 miles between changes with no issue of oil clarity. It would use less than 1/2 a quart between changes, mostly during the last 1,000 miles of the 6.
Now going 5,000 between changes on the ZX-14 and have experienced zero level drop between changes. The first couple of changes, the drain oil was a little cloudy, but that has cleared up, which is why I postulated that dirty-looking drain oil could be sludge from a previous fill of a different oil.
I've never sent an oil sample to a lab because I just don't feel it's necessary. Every motor is different, everyone ride a little different and I believe it's entirely possible someone may experience different results using the same oil as someone else.
Always paid $8-9 pe quart for Amsoil and Mobil 1 4T. The Mobil 1 semi-syn mentioned earlier as marketed by Triumph must be pretty good stuff, because their 4T full syn used to be the Triumph-recommended and labeled oil of choice.
'07 CPB Blue; ZGST windscreen with MRA X-screen adjustable spoiler, tube bar adaptor, PC III, ATRE,BMC air filter, modified stock seat with 2nd Look cover,Scorpion Flame Ti slip-ons, Galfer rotors front and rear, braided-stainless lines, C-F 10R front fender, C-F hugger, C-F inner fairing panels, painted foreman's fins with faux C-F inlay, polished rim lips wired for heated gear and accessories, Givi V35 side bags and E41 topcase with SW-Motech qd mounts