lt50 2 stroke oil?
If it's a 2-stroke Suzuki 50 (LT-50 until about 2000, LT-A50 from about 2001-2005?, LT-Z50 four stroke thereafter) it's oil injected and there should be an oil tank under the seat. A lever under the rear of the seat releases it so you can lift it up. The tank's cap says "OIL" right on it. Obviously don't premix.
Any good quality 2-stroke oil will work great. I buy NAPA's brand in quarts because that little engine doesn't drink very much of it.
That's a great little machine you have there. My son LOVES his and rides wherever we do. We have the machine restricted to about 13-15 MPH which still gives him enough power to climb some surprisingly steep hills.