Hi guys, I have done some research and I might be lucky and score a manual for this one....However from what I have gleaned, the RST131ES is a 2 stroke and as such would require no "valve-saver" in the fuel mix.
25:1 with a good quality 2stroke oil into ULP should do the trick.
BTW Yoda55, the original post you replied to is over 5 years old and Smouch is no longer a current member. wink
I will give you a heads-up if I score the manual for you. grin
cheers2

Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member.
Kindest Regards, Darryl grin