Q2: [Are there] any problems [caused by using Evinrude XD50 oil in an older outboard engine]?
BACKSTORY: I pre-mix my boat's fuel at 50:1 ratio for gasoline-to-oil. I usually buy my two-cycle oil at my Evinrude dealer who sells it out of a [55-gallon] drum and decants the oil into your container. I used Evinrude XD25 for many years. When XD25 was discontinued I used XD30 (red). Both XD25 and XD30 were much better than West Marine and other oils at keeping the engine's spark plugs clean. This year when I bought oil I got XD-50 (blue). My guy said it was better, and XD30 and XD25 were no longer available.
An online site has also replaced the XD30 with XD50.
unidentified web site wrote:We have replaced XD30 with XD50, all clients using XD30 should now purchase XD50. XD50 is a superior TCW3 alternative.
The only difference [between XD50 and XD30] I see is that [XD50] is a synthetic blend.