I have been afraid to use synthetic or Amsoil in respect to 46 yr old bearings. Has anyone used this in old pre-mix 2 strokes?
I use either the Honda GM-2 two-stroke oil, or Golden Spectro. Use the Honda oil in my NS400R, (oil-injection), and in my dirtbikes, (Pre-Mix) since it says it's for both injection and pre-mix. Some oils are one or the other, (I cannot see how it would make a difference).
No problems from the Honda oil, and next to no smoke. The NS only smokes when cold starting, but when warm, it's pretty clear, (except for the occasional blue puff when romping on it). The dirtbikes always smoke a little, but I run 'em a little rich, around 32:1, maybe a little more, (sometimes 25:1). Backing off though, and will probably settle on 36-40:1.
The Golden Spectro comes HIGHLY recommended by guys I know that race vintage MX, and push their machines hard. Low fouling, little smoke, great wear characteristics. I might run some in the NS and see how differently it smokes.
http://www.spectro-oils.com/products/offroad/2stroke.asp