If you spring for good oil like amsoil 50:1 is no problem. I run alot of my old sleds on 40:1 even with cheap oil alot depends on how and how much you will ride them.
Take Care Andy
1997zrt600,1995zr580,1993 polaris750storm,1994 yamaha timberwolf
I love vintage sleds got 25 or so lol, john deere is my favorite old sled