BajaRon ... what do you recommend for the older 09's GS's . I know you use Amsoil . Witch Amsoil for the older v-twins ?
Yes, I use Amsoil MCF 10w-40. It is a true, fully synthetic lubricant and I believe the best fit for the Spyder. The only time the lower number comes into play is at cold start-up. You want a lubricant thin enough to give you good flow when cold, and thick enough to give you good protection. As you can see from the chart provided by Gwolf, a 10w oil will flow very well to temperatures much lower than most Spyders will ever see. The original application for the 998 Rotax was in the Aprilia Tuono. The recommended lubricant for that application is 20w-50. When they put the same engine in the Spyder, BRP recommended 10w-40. I assume because most crotch rocket motors spend a fair amount of time near redline. BRP probably expected Spyder riders to be a bit less aggressive.
Some Spyder owners in very hot climates run 20w-50 with good results. Even a 20w oil will flow quite nicely at the temps most Spyder see cold. However, if you're leaving your Spyder out in sub-zero temps for long periods, you might be better with a 5w.
Remember that the larger the spread between the low and high numbers. The less stable the oil is. Getting a wider spread, when not necessary, gives you an oil that will break down more quickly. This is doubly true for a blended oil which is typically 10% synthetic and 90% standard mineral oil. The oil currently recommended for both the 998 and the 1330 tends to shear down to 20w around 5,000 miles. This is why the recommended service interval on the 998 is 4,500 miles. Right about the time the oil starts to go away. It is a mystery as to why BRP now recommends a 9,300 mile service interval on the 1330. It is our experience that both the 998 and the 1330 shear and wear the oil at about the same rate. This means you're running your 1330 for around 4,000 miles on a 20w lubricant.
Most Spyders never see the really cold starts that a 5w oil is designed for. Not to mention, a true, fully synthetic lubricant will do better at both ends of the scale than a blended or additive type synthetic. If anything, Spyders tend more to run in the upper area of the temp scale. And the upper number of the oil is where the engine spends nearly its entire running life. While it is true that most wear occurs at start-up (assuming that the oil is the correct viscosity at operating temperature). A true synthetic lubricant stays on and continues to coat parts between starts better than other lubricants. And will flow better than a similar viscosity lubricant when cold.
BRP has drastically reduced their lubricant lineup over the years. The relatively few lubricants that they offer have to cover everything from a snowmobile that typically sits outside in very cold weather, to our Spyders. The snowmobile MUST have a very thin start-up lubricant. Whereas our Spyders will do OK with it. It isn't necessarily ideal or a best fit.