In a saucepan combine sugar, flour, 1/2 tsp. salt, pineapple juice and eggs.
Stir and cook over medium heat until thickened.
Remove from heat add lemon juice and cool to room temp.
Bring water to a boil add oil, remaining salt, and cook pasta until soft.
Rinse under cold water and drain.
In a large bowl combine pasta, egg mixture, oranges, pineapple and whip topping.
Mix well, refrigerate overnight or until chilled.
Before serving, add marshmallows.